Systems and methods for allocating bandwidth by an intermediary for flow control

ABSTRACT

The present disclosure is directed towards systems and methods for allocating a bandwidth credit or an annuity of bandwidth credit to a sender by an intermediary deployed between the sender and a receiver. The sender may be allocated a bandwidth credit or an annuity of bandwidth credit which may identify an amount of data the sender may transmit over a predetermined time period to the receiver, via the intermediary. The intermediary may determine an allocation of a one-time bandwidth credit based on the determination that a difference between the rate of transmission of the sender and the bandwidth usage of the sender falls below a predetermined threshold of the bandwidth credit. The intermediary may determine an annuity of bandwidth credit based on a determination that a difference between the bandwidth usage of the sender over the annuity period and the annuity of bandwidth credit exceeds a predetermined threshold.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/103,712, entitled “Systems And Methods For Allocating Bandwidth By AnIntermediary For Flow Control”, filed on Oct. 8, 2008, which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present application generally relates to data communicationnetworks. In particular, the present application relates to systems andmethods for flow control of data communicated over a network using anetwork structure component, such as an intermediary.

BACKGROUND OF THE INVENTION

Network traffic may be transmitted over a network between clients andservers traversing one or more network-infrastructure components. Eachof the clients may transmit different size data to the servers as wellas transmit as different transmission rates. Likewise, each of theservers may transmit different amounts of data and transmit at differenttransmission rates to one or more clients. The network-infrastructurecomponents may process the network traffic further to cause changes tothe size of data and transmission rate of data between the clients andservers. The clients and servers may not be aware of the changesoccurring from processing by the network-infrastructure components. Anymanagement of bandwidth from a client or server perspective may bechallenging or ineffective as the network-infrastructure componentsimpact the use of bandwidth between the clients and servers. Forexample, if the data stream is compressed by a network component with acompression format in which the compression ratios of the compresseddata packets vary, the bandwidth use also varies accordingly.

BRIEF SUMMARY OF THE INVENTION

In the present solution, one or more intermediaries may intercept thedata transmitted between the client and the server and direct the data'sflow. An intermediary may determine the bandwidth used by the client andthe server, as well as the bandwidth available, based on monitoring ofthe bandwidth between the sender and the receiver, or even monitoring ofthe network as a whole. Sometimes, in response to the monitoring, theintermediary may determine that an additional transmission of data fromthe client to the server is possible. In some embodiments, theintermediary may determine that an additional amount of bandwidth over apredetermined period of time for the client to send to the server ispossible. In such instances, the intermediary may utilize bandwidthmonitoring to determine a bandwidth credit which may identify an amountof additional data the sender may transmit to the server via theintermediary. In some embodiments, the intermediary may utilizebandwidth monitoring to determine an annuity of bandwidth credit whichmay identify an amount of bandwidth the client may use for apredetermined amount of time.

The present disclosure thus also relates to systems and methods forallocation of bandwidth credit or the annuity of bandwidth credit basedon the monitored information. The monitored information may compriseinformation on bandwidth metrics relating to the client, the server andthe network. The bandwidth credit may identify the amount of data whichmay be transferred over the intermediary in a one-time transmission orover a period of time. Therefore, the methods and systems disclosedaddress the issue of efficient data flow control of the compressed datastream while maximizing the efficiency and full utilization of thenetwork's available resources.

In some aspects, the present solution is related to systems and methodsmethod for allocating bandwidth credit of a sender by comparing theallocated bandwidth credit to a measurement of data transmission ratevia the intermediary and compression of data by the intermediary. Insome embodiments, the present solution is related to an intermediary forallocating bandwidth credit of a sender by comparing the allocatedbandwidth credit to a measurement of data transmission rate via theintermediary and compression of data by the intermediary. The presentsolution also relates to allocating a bandwidth credit to a sender or areceiver. The bandwidth credit may identify of an amount of data thesender may transmit over a predetermined time period to the one or morereceivers via an intermediary. The intermediary may compress data of thesender transmitted to the at least one receiver using any compressionmethod or any compression ratio. In some embodiments the intermediarymay be monitoring bandwidth usage by determining a ratio of compressionof data of the sender compressed by the intermediary and a rate oftransmission of compressed data of the sender transmitted by theintermediary. The data of the sender may be transmitted by theintermediary to one or more receivers. The intermediary may determinethat a difference between the rate of transmission of the sender and thebandwidth usage of the sender falls below a predetermined threshold ofthe bandwidth credit. The intermediary may, in response to thedetermination, communicate an allocation of a one-time bandwidth creditto the sender based on the difference.

In some embodiments, the intermediary may allocate to a plurality ofsenders a plurality of bandwidth credits. Each of the plurality ofbandwidth credits may further identify an amount of data each of theplurality of senders may transmit over a predetermined time period toone or more receivers. In some embodiments, the intermediary maydetermine that the difference between the rate of transmission of thesender and the bandwidth usage of the sender falls within apredetermined threshold range of the bandwidth credit. In manyembodiments, the one-time bandwidth credit may further identify a secondpredetermined amount of data the sender may send to one or morereceivers within the predetermined time period. In some embodiments, theone-time bandwidth credit further identifies a second predeterminedamount of data the sender may send to one or more receivers within asecond predetermined amount of time. In a plurality of embodiments, theone-time bandwidth credit further identifies a predetermined amount ofadditional of data the sender may send to a second group of one or morereceivers via the intermediary. In a variety of embodiments, theintermediary monitors the bandwidth usage by determining a rate oftransmission of data of one or more receivers and transmitted by theintermediary to the sender. In a number of embodiments, the intermediarydetermines, in response to monitoring, that a difference between therate of transmission of the sender and the bandwidth usage of the senderfalls below a predetermined threshold of the bandwidth credit.

In many embodiments, the intermediary allocates to one or more receiversa second bandwidth credit identifying an amount of data one or morereceivers may transmit over a predetermined time period to the at leastone sender. The intermediary may monitor the bandwidth usage of one ormore receivers by determining a ratio of compression of data of the oneor more receivers compressed by the intermediary and a rate oftransmission of compressed data of the one or more receivers transmittedby the intermediary to one or more senders. The intermediary determinesthat a second difference between the rate of transmission of the one ormore receivers and the bandwidth usage of one or more receivers fallsbelow a second predetermined threshold of the second bandwidth credit.The intermediary, in response to the determination, may communicate anallocation of a second one-time bandwidth credit to the one or morereceivers.

In some aspects, the present solution is related to systems and methodsfor renewing an annuity of bandwidth credit of the sender by determiningthe allocated bandwidth credit to a measurement of data transmissionrate via the intermediary and compression of data by the intermediary.In some embodiments, the present disclosure is related to anintermediary for renewing an annuity of bandwidth credit of the senderby determining the allocated bandwidth credit to a measurement of datatransmission rate via the intermediary and compression of data by theintermediary. In some embodiments, the intermediary is allocating anannuity of bandwidth credit to a sender. The annuity of bandwidth creditmay identify an amount of data the sender may transmit within apredetermined annuity period to one or more receivers via anintermediary. In some embodiments, the intermediary monitors a bandwidthusage of the sender between the intermediary and one or more receiversover the predetermined annuity period based on determining a ratio ofcompression of data of the sender compressed by the intermediary and arate of transmission of compressed data of the sender transmitted by theintermediary. In a number of embodiments, the intermediary determinesthat a difference between the bandwidth usage of the sender over theannuity period and the annuity of bandwidth credit exceeds apredetermined threshold. The intermediary may communicate, in responseto the determination, a renewed allocation of the annuity bandwidthcredit to the sender based on a second predetermined ratio ofcompression.

In some embodiments, the annuity of bandwidth credit further identifiesa plurality of amounts of data the sender may transmit over a pluralityof predetermined annuity periods to one or more receivers. In manyembodiments, the intermediary monitors the bandwidth usage of the senderbetween the intermediary and one or more receivers over thepredetermined annuity period based on determining a ratio of compressionof data of the sender compressed by the intermediary and a rate oftransmission of compressed data of the sender received by one or morereceivers. In a number of embodiments, the renewed allocation furtheridentifies a second amount of data the sender may transmit over a secondpredetermined annuity period to one or more receivers via anintermediary. The renewed allocation may also further identify a secondamount of data the sender may transmit over the predetermined annuityperiod to one or more receivers via an intermediary.

In some embodiments, the one or more receivers are allocated a secondannuity of bandwidth credit identifying an amount of data a receiver maytransmit over a second predetermined annuity period to the sender viathe intermediary. The intermediary may monitor a second bandwidth usageof the one or more receivers between the intermediary and the senderover the second predetermined annuity period based on determining aratio of compression of data of one or more receivers compressed by theintermediary. The intermediary may also monitor a second bandwidth usageof a receiver by determining a rate of transmission of compressed dataof the one or more receivers transmitted by the intermediary. In someembodiments, the intermediary determines that a difference between thesecond bandwidth usage and the second annuity of bandwidth creditexceeds a predetermined threshold or is within a predetermined thresholdrange. In response to the determination, the intermediary maycommunicate a second renewed allocation of the annuity bandwidth creditto one or more receivers.

In some aspects, the present solution relates to a system and method forestablishing one of a bandwidth credit or the annuity of a bandwidthcredit of one or more senders using a measurement of data transmissionrate via the intermediary and compression of data by the intermediary. Abandwidth allocator of an intermediary, in some embodiments, allocatesto one or more senders a bandwidth credit identifying an amount of dataone or more senders may transmit over a predetermined time period to oneor more receivers via an intermediary. A bandwidth monitor of theintermediary may monitor the bandwidth usage by determining a ratio ofcompression of data of the sender compressed by the intermediary and arate of transmission of compressed data of the sender transmitted by theintermediary to one or more receivers. In some embodiments, a flowcontroller of the intermediary determines that a difference between therate of transmission of the sender and the bandwidth usage of the senderfalls below a predetermined threshold of the bandwidth credit. In manyembodiments, the network optimization engine communicates, in responsethe determination, an allocation of a one-time bandwidth credit to thesender based on the difference.

Any embodiment mentioned or described herein may be combined with anyother embodiment mentioned or described to create any combination ofembodiments or functionalities of the embodiments. The details ofembodiments of the disclosure are set forth in the accompanying drawingsand the description below.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe disclosure will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a block diagram illustrating some embodiments of a networkenvironment for a client to access a server via one or more networkoptimization appliances;

FIG. 1B is a block diagram illustrating some embodiments of a networkenvironment for a client to access a server via one or more networkoptimization appliances in conjunction with other network appliances;

FIG. 1C is a block diagram illustrating some embodiments of a networkenvironment for a client to access a server via a single networkoptimization appliance deployed stand-alone or in conjunction with othernetwork appliances;

FIGS. 1E and 1F are block diagrams illustrating some embodiments of acomputing device;

FIG. 2A is a block diagram illustrating some embodiments of an appliancefor processing communications between a client and a server;

FIG. 2B is a block diagram illustrating some embodiments of a clientand/or server deploying the network optimization features of theappliance;

FIG. 3 is a block diagram illustrating some embodiments of a client forcommunicating with a server using the network optimization feature;

FIG. 4 is a block diagram illustrating some embodiments of a sender suchas a client transmitting a data stream to a receiver, such as a servervia an appliance 200.

FIG. 5 is a flow diagram illustrating some embodiments of a method for aflow control of a data stream communicated via a network between aclient and a server.

FIG. 6 is a flow diagram illustrating some embodiments of a client or aserver side method for a flow control of a data stream communicated viaa network between a client and a server.

FIG. 7 is a is a block diagram illustrating some embodiments ofbandwidth allocation relating to a communication between a sender and areceiver.

FIG. 8 is a flow diagram illustrating some embodiments of a method forbandwidth allocation relating to a communication between a sender and areceiver.

The features and advantages of the present disclosure will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of reading the description of the various embodiments ofthe present disclosure below, the following descriptions of the sectionsof the specification and their respective contents may be helpful:

-   -   Section A describes a network environment and computing        environment useful for practicing an embodiment of the present        disclosure;    -   Section B describes embodiments of a system and appliance        architecture for accelerating delivery of a computing        environment to a remote user;    -   Section C describes embodiments of a client agent for        accelerating communications between a client and a server; and    -   Section D describes embodiments of systems and methods for a        more efficient control of a flow of a data stream communicated        via a network between a client and a server and traversing an        intermediary.    -   Section E describes embodiments of systems and methods for        allocation of bandwidth credit and allocation of annuity of        bandwidth credit to a sender transmitting a data, via an        intermediary, to a receiver on a network.

A. Network and Computing Environment

Prior to discussing the specifics of embodiments of the systems andmethods of an appliance and/or client, it may be helpful to discuss thenetwork and computing environments in which such embodiments may bedeployed. Referring now to FIG. 1A, an embodiment of a networkenvironment is depicted. In brief overview, the network environment hasone or more clients 102 a-102 n (also generally referred to as localmachine(s) 102, or client(s) 102) in communication with one or moreservers 106 a-106 n (also generally referred to as server(s) 106, orremote machine(s) 106) via one or more networks 104, 104′, 104″. In someembodiments, a client 102 communicates with a server 106 via one or morenetwork optimization appliances 200, 200′ (generally referred to asappliance 200). In one embodiment, the network optimization appliance200 is designed, configured or adapted to optimize Wide Area Network(WAN) network traffic. In some embodiments, a first appliance 200 worksin conjunction or cooperation with a second appliance 200′ to optimizenetwork traffic. For example, a first appliance 200 may be locatedbetween a branch office and a WAN connection while the second appliance200′ is located between the WAN and a corporate Local Area Network(LAN). The appliances 200 and 200′ may work together to optimize the WANrelated network traffic between a client in the branch office and aserver on the corporate LAN.

Although FIG. 1A shows a network 104, network 104′ and network 104″(generally referred to as network(s) 104) between the clients 102 andthe servers 106, the clients 102 and the servers 106 may be on the samenetwork 104. The networks 104, 104′, 104″ can be the same type ofnetwork or different types of networks. The network 104 can be alocal-area network (LAN), such as a company Intranet, a metropolitanarea network (MAN), or a wide area network (WAN), such as the Internetor the World Wide Web. The networks 104, 104′, 104″ can be a private orpublic network. In one embodiment, network 104′ or network 104″ may be aprivate network and network 104 may be a public network. In someembodiments, network 104 may be a private network and network 104′and/or network 104″ a public network. In another embodiment, networks104, 104′, 104″ may be private networks. In some embodiments, clients102 may be located at a branch office of a corporate enterprisecommunicating via a WAN connection over the network 104 to the servers106 located on a corporate LAN in a corporate data center.

The network 104 may be any type and/or form of network and may includeany of the following: a point to point network, a broadcast network, awide area network, a local area network, a telecommunications network, adata communication network, a computer network, an ATM (AsynchronousTransfer Mode) network, a SONET (Synchronous Optical Network) network, aSDH (Synchronous Digital Hierarchy) network, a wireless network and awireline network. In some embodiments, the network 104 may comprise awireless link, such as an infrared channel or satellite band. Thetopology of the network 104 may be a bus, star, or ring networktopology. The network 104 and network topology may be of any suchnetwork or network topology as known to those ordinarily skilled in theart capable of supporting the operations described herein.

As depicted in FIG. 1A, a first network optimization appliance 200 isshown between networks 104 and 104′ and a second network optimizationappliance 200′ is also between networks 104′ and 104″. In someembodiments, the appliance 200 may be located on network 104. Forexample, a corporate enterprise may deploy an appliance 200 at thebranch office. In other embodiments, the appliance 200 may be located onnetwork 104′. In some embodiments, the appliance 200′ may be located onnetwork 104′ or network 104″. For example, an appliance 200 may belocated at a corporate data center. In one embodiment, the appliance 200and 200′ are on the same network. In another embodiment, the appliance200 and 200′ are on different networks.

In one embodiment, the appliance 200 is a device for accelerating,optimizing or otherwise improving the performance, operation, or qualityof service of any type and form of network traffic. In some embodiments,the appliance 200 is a performance enhancing proxy. In otherembodiments, the appliance 200 is any type and form of WAN optimizationor acceleration device, sometimes also referred to as a WAN optimizationcontroller. In one embodiment, the appliance 200 is any of the productembodiments referred to as WANScaler manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. In other embodiments, the appliance 200includes any of the product embodiments referred to as BIG-IP linkcontroller and WANjet manufactured by F5 Networks, Inc. of Seattle,Wash. In another embodiment, the appliance 200 includes any of the WXand WXC WAN acceleration device platforms manufactured by JuniperNetworks, Inc. of Sunnyvale, Calif. In some embodiments, the appliance200 includes any of the steelhead line of WAN optimization appliancesmanufactured by Riverbed Technology of San Francisco, Calif. In otherembodiments, the appliance 200 includes any of the WAN related devicesmanufactured by Expand Networks Inc. of Roseland, N.J. In oneembodiment, the appliance 200 includes any of the WAN related appliancesmanufactured by Packeteer Inc. of Cupertino, Calif., such as thePacketShaper, iShared, and SkyX product embodiments provided byPacketeer. In yet another embodiment, the appliance 200 includes any WANrelated appliances and/or software manufactured by Cisco Systems, Inc.of San Jose, Calif., such as the Cisco Wide Area Network ApplicationServices software and network modules, and Wide Area Network engineappliances.

In some embodiments, the appliance 200 provides application and dataacceleration services for branch-office or remote offices. In oneembodiment, the appliance 200 includes optimization of Wide Area FileServices (WAFS). In another embodiment, the appliance 200 acceleratesthe delivery of files, such as via the Common Internet File System(CIFS) protocol. In other embodiments, the appliance 200 providescaching in memory and/or storage to accelerate delivery of applicationsand data. In one embodiment, the appliance 205 provides compression ofnetwork traffic at any level of the network stack or at any protocol ornetwork layer. In another embodiment, the appliance 200 providestransport layer protocol optimizations, flow control, performanceenhancements or modifications and/or management to accelerate deliveryof applications and data over a WAN connection. For example, in oneembodiment, the appliance 200 provides Transport Control Protocol (TCP)optimizations. In other embodiments, the appliance 200 providesoptimizations, flow control, performance enhancements or modificationsand/or management for any session or application layer protocol. Furtherdetails of the optimization techniques, operations and architecture ofthe appliance 200 are discussed below in Section B.

Still referring to FIG. 1A, the network environment may includemultiple, logically-grouped servers 106. In these embodiments, thelogical group of servers may be referred to as a server farm 38. In someof these embodiments, the serves 106 may be geographically dispersed. Insome cases, a farm 38 may be administered as a single entity. In otherembodiments, the server farm 38 comprises a plurality of server farms38. In one embodiment, the server farm executes one or more applicationson behalf of one or more clients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or metropolitan-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Deployed with Other Appliances.

Referring now to FIG. 1B, another embodiment of a network environment isdepicted in which the network optimization appliance 200 is deployedwith one or more other appliances 205, 205′ (generally referred to asappliance 205 or second appliance 205) such as a gateway, firewall oracceleration appliance. For example, in one embodiment, the appliance205 is a firewall or security appliance while appliance 205′ is a LANacceleration device. In some embodiments, a client 102 may communicateto a server 106 via one or more of the first appliances 200 and one ormore second appliances 205.

One or more appliances 200 and 205 may be located at any point in thenetwork or network communications path between a client 102 and a server106. In some embodiments, a second appliance 205 may be located on thesame network 104 as the first appliance 200. In other embodiments, thesecond appliance 205 may be located on a different network 104 as thefirst appliance 200. In yet another embodiment, a first appliance 200and second appliance 205 is on the same network, for example network104, while the first appliance 200′ and second appliance 205′ is on thesame network, such as network 104″.

In one embodiment, the second appliance 205 includes any type and formof transport control protocol or transport later terminating device,such as a gateway or firewall device. In one embodiment, the appliance205 terminates the transport control protocol by establishing a firsttransport control protocol connection with the client and a secondtransport control connection with the second appliance or server. Inanother embodiment, the appliance 205 terminates the transport controlprotocol by changing, managing or controlling the behavior of thetransport control protocol connection between the client and the serveror second appliance. For example, the appliance 205 may change, queue,forward or transmit network packets in manner to effectively terminatethe transport control protocol connection or to act or simulate asterminating the connection.

In some embodiments, the second appliance 205 is a performance enhancingproxy. In one embodiment, the appliance 205 provides a virtual privatenetwork (VPN) connection. In some embodiments, the appliance 205provides a Secure Socket Layer VPN (SSL VPN) connection. In otherembodiments, the appliance 205 provides an IPsec (Internet ProtocolSecurity) based VPN connection. In some embodiments, the appliance 205provides any one or more of the following functionality: compression,acceleration, load-balancing, switching/routing, caching, and TransportControl Protocol (TCP) acceleration.

In one embodiment, the appliance 205 is any of the product embodimentsreferred to as Access Gateway, Application Firewall, ApplicationGateway, or NetScaler manufactured by Citrix Systems, Inc. of Ft.Lauderdale, Fla. As such, in some embodiments, the appliance 205includes any logic, functions, rules, or operations to perform servicesor functionality such as SSL VPN connectivity, SSL offloading,switching/load balancing, Domain Name Service resolution, LANacceleration and an application firewall.

In some embodiments, the appliance 205 provides a SSL VPN connectionbetween a client 102 and a server 106. For example, a client 102 on afirst network 104 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104″ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, a clientagent intercepts communications of the client 102 on the first network104, encrypts the communications, and transmits the communications via afirst transport layer connection to the appliance 205. The appliance 205associates the first transport layer connection on the first network 104to a second transport layer connection to the server 106 on the secondnetwork 104. The appliance 205 receives the intercepted communicationfrom the client agent, decrypts the communications, and transmits thecommunication to the server 106 on the second network 104 via the secondtransport layer connection. The second transport layer connection may bea pooled transport layer connection. In one embodiment the appliance 205provides an end-to-end secure transport layer connection for the client102 between the two networks 104, 104′

In one embodiments, the appliance 205 hosts an intranet internetprotocol or intranetIP address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as aninternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 205,the appliance 205 establishes, assigns or otherwise provides anIntranetIP, which is network identifier, such as IP address and/or hostname, for the client 102 on the second network 104′. The appliance 205listens for and receives on the second or private network 104′ for anycommunications directed towards the client 102 using the client'sestablished IntranetIP. In one embodiment, the appliance 205 acts as oron behalf of the client 102 on the second private network 104.

In some embodiment, the appliance 205 has an encryption engine providinglogic, business rules, functions or operations for handling theprocessing of any security related protocol, such as SSL or TLS, or anyfunction related thereto. For example, the encryption engine encryptsand decrypts network packets, or any portion thereof, communicated viathe appliance 205. The encryption engine may also setup or establish SSLor TLS connections on behalf of the client 102 a-102 n, server 106 a-106n, or appliance 200, 205. As such, the encryption engine providesoffloading and acceleration of SSL processing. In one embodiment, theencryption engine uses a tunneling protocol to provide a virtual privatenetwork between a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine uses an encryption processor. Inother embodiments, the encryption engine includes executableinstructions running on an encryption processor.

In some embodiments, the appliance 205 provides one or more of thefollowing acceleration techniques to communications between the client102 and server 106: 1) compression, 2) decompression, 3) TransmissionControl Protocol pooling, 4) Transmission Control Protocol multiplexing,5) Transmission Control Protocol buffering, and 6) caching. In oneembodiment, the appliance 200 relieves servers 106 of much of theprocessing load caused by repeatedly opening and closing transportlayers connections to clients 102 by opening one or more transport layerconnections with each server 106 and maintaining these connections toallow repeated data accesses by clients via the Internet. This techniqueis referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 205 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 205, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 205 and the destination address is changedfrom that of appliance 205 to that of the requesting client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement expected by theclient 102 on the appliance's 205 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 205 provides switching orload-balancing functionality for communications between the client 102and server 106. In some embodiments, the appliance 205 distributestraffic and directs client requests to a server 106 based on layer 4payload or application-layer request data. In one embodiment, althoughthe network layer or layer 2 of the network packet identifies adestination server 106, the appliance 205 determines the server 106 todistribute the network packet by application information and datacarried as payload of the transport layer packet. In one embodiment, ahealth monitoring program of the appliance 205 monitors the health ofservers to determine the server 106 for which to distribute a client'srequest. In some embodiments, if the appliance 205 detects a server 106is not available or has a load over a predetermined threshold, theappliance 205 can direct or distribute client requests to another server106.

In some embodiments, the appliance 205 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts' a DNSrequest transmitted by the client 102. In one embodiment, the appliance205 responds to a client's DNS request with an IP address of or hostedby the appliance 205. In this embodiment, the client 102 transmitsnetwork communication for the domain name to the appliance 200. Inanother embodiment, the appliance 200 responds to a client's DNS requestwith an IP address of or hosted by a second appliance 200′. In someembodiments, the appliance 205 responds to a client's DNS request withan IP address of a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 205 provides applicationfirewall functionality for communications between the client 102 andserver 106. In one embodiment, a policy engine 295′ provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall protects against denial of service (DoS) attacks.In other embodiments, the appliance inspects the content of interceptedrequests to identify and block application-based attacks. In someembodiments, the rules/policy engine includes one or more applicationfirewall or security control policies for providing protections againstvarious classes and types of web or Internet based vulnerabilities, suchas one or more of the following: 1) buffer overflow, 2) CGI-BINparameter manipulation, 3) form/hidden field manipulation, 4) forcefulbrowsing, 5) cookie or session poisoning, 6) broken access control list(ACLs) or weak passwords, 7) cross-site scripting (XSS), 8) commandinjection, 9) SQL injection, 10) error triggering sensitive informationleak, 11) insecure use of cryptography, 12) server misconfiguration, 13)back doors and debug options, 14) website defacement, 15) platform oroperating systems vulnerabilities, and 16) zero-day exploits. In anembodiment, the application firewall of the appliance provides HTML formfield protection in the form of inspecting or analyzing the networkcommunication for one or more of the following: 1) required fields arereturned, 2) no added field allowed, 3) read-only and hidden fieldenforcement, 4) drop-down list and radio button field conformance, and5) form-field max-length enforcement. In some embodiments, theapplication firewall of the appliance 205 ensures cookies are notmodified. In other embodiments, the appliance 205 protects againstforceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall appliance 205protects any confidential information contained in the networkcommunication. The appliance 205 may inspect or analyze any networkcommunication in accordance with the rules or polices of the policyengine to identify any confidential information in any field of thenetwork packet. In some embodiments, the application firewall identifiesin the network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay include these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall may takea policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

Although generally referred to as a network optimization or firstappliance 200 and a second appliance 205, the first appliance 200 andsecond appliance 205 may be the same type and form of appliance. In someembodiments an appliance 205 or an appliance 200 may be any type ofdevice or a structure capable of affecting a data stream traversing iton the way from a client to a server or vice versa. In one embodiment,the second appliance 205 may perform the same functionality, or portionthereof, as the first appliance 200, and vice-versa. For example, thefirst appliance 200 and second appliance 205 may both provideacceleration techniques. In one embodiment, the first appliance mayperform LAN acceleration while the second appliance performs WANacceleration, or vice-versa. In another example, the first appliance 200may also be a transport control protocol terminating device as with thesecond appliance 205. Furthermore, although appliances 200 and 205 areshown as separate devices on the network, the appliance 200 and/or 205could be a part of any client 102 or server 106.

Referring now to FIG. 1C, other embodiments of a network environment fordeploying the appliance 200 are depicted. In another embodiment asdepicted on the top of FIG. 1C, the appliance 200 may be deployed as asingle appliance or single proxy on the network 104. For example, theappliance 200 may be designed, constructed or adapted to perform WANoptimization techniques discussed herein without a second cooperatingappliance 200′. In other embodiments as depicted on the bottom of FIG.1C, a single appliance 200 may be deployed with one or more secondappliances 205. For example, a WAN acceleration first appliance 200,such as a Citrix WANScaler appliance, may be deployed with a LANaccelerating or Application Firewall second appliance 205, such as aCitrix NetScaler appliance.

Computing Device

The client 102, server 106, and appliance 200 and 205 may be deployed asand/or executed on any type and form of computing device, such as acomputer, network device or appliance capable of communicating on anytype and form of network and performing the operations described herein.FIGS. 1C and 1D depict block diagrams of a computing device 100 usefulfor practicing an embodiment of the client 102, server 106 or appliance200. As shown in FIGS. 1C and 1D, each computing device 100 may includea central processing unit 101, and a main memory unit 122. As shown inFIG. 1C, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1C, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1C depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1D the main memory 122 maybe DRDRAM.

FIG. 1D depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1C, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1D depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130via HyperTransport, Rapid I/O, or InfiniBand. FIG. 1D also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 using a localinterconnect bus while communicating with I/O device 130 directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein. A wide variety of I/O devices 130 a-130 n may bepresent in the computing device 100. Input devices include keyboards,mice, trackpads, trackballs, microphones, and drawing tablets. Outputdevices include video displays, speakers, inkjet printers, laserprinters, and dye-sublimation printers. The I/O devices 130 may becontrolled by an I/O controller 123 as shown in FIG. 1C. The I/Ocontroller may control one or more I/O devices such as a keyboard 126and a pointing device 127, e.g., a mouse or optical pen. Furthermore, anI/O device may also provide storage 128 and/or an installation medium116 for the computing device 100. In still other embodiments, thecomputing device 100 may provide USB connections to receive handheld USBstorage devices such as the USB Flash Drive line of devices manufacturedby Twintech Industry, Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1C and 1D typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which aremanufactured by Microsoft Corporation of Redmond, Wash.; MacOS,manufactured by Apple Computer of Cupertino, Calif.; OS/2, manufacturedby International Business Machines of Armonk, N.Y.; and Linux, afreely-available operating system distributed by Caldera Corp. of SaltLake City, Utah, or any type and/or form of a Unix operating system,among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

B. System and Appliance Architecture

Referring now to FIG. 2A, an embodiment of a system environment andarchitecture of an appliance 200 for delivering and/or operating acomputing environment on a client is depicted. In some embodiments, aserver 106 includes an application delivery system 290 for delivering acomputing environment or an application and/or data file to one or moreclients 102. In brief overview, a client 102 is in communication with aserver 106 via network 104 and appliance 200. For example, the client102 may reside in a remote office of a company, e.g., a branch office,and the server 106 may reside at a corporate data center. The client 102has a client agent 120, and a computing environment 215. The computingenvironment 215 may execute or operate an application that accesses,processes or uses a data file. The computing environment 215,application and/or data file may be delivered via the appliance 200and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 215, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 215 by the application delivery system 290. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. In another embodiment, the appliance 200 controls,manages, or adjusts the transport layer protocol to accelerate deliveryof the computing environment. In some embodiments, the appliance 200uses caching and/or compression techniques to accelerate delivery of acomputing environment.

In some embodiments, the application delivery management system 290provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 295. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 290 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 290 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 290 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 290 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 290, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 290, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 290 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 215 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 290 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 215 on client 102.

In some embodiments, the application delivery system 290 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 290 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 290 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 290 includes a policyengine 295 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 295 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 295 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 290 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 290 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 290 enumerates a plurality of application programsavailable to the client 102. The application delivery system 290receives a request to execute an enumerated application. The applicationdelivery system 290 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 290 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 290may select a method of execution of the application enabling the clientor local machine 102 to execute the application program locally afterretrieving a plurality of application files comprising the application.In yet another embodiment, the application delivery system 290 mayselect a method of execution of the application to stream theapplication via the network 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiment the server 106 may display output to the client 102 using anythin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server. In some embodiments, any ofthe applications may comprise any type of hosted service or products,such as GoToMeeting™ provided by Citrix Online Division, Inc. of SantaBarbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif.,or Microsoft Office Live Meeting provided by Microsoft Corporation ofRedmond, Wash.

Example Appliance Architecture

FIG. 2A also illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting in any manner. Theappliance 200 may include any type and form of computing device 100,such as any element or portion described in conjunction with FIGS. 1Dand 1E above. In brief overview, the appliance 200 has one or morenetwork ports 266A-226N and one or more networks stacks 267A-267N forreceiving and/or transmitting communications via networks 104. Theappliance 200 also has a network optimization engine 250 for optimizing,accelerating or otherwise improving the performance, operation, orquality of any network traffic or communications traversing theappliance 200.

The appliance 200 includes or is under the control of an operatingsystem. The operating system of the appliance 200 may be any type and/orform of Unix operating system although the disclosure is not so limited.As such, the appliance 200 can be running any operating system such asany of the versions of the Microsoft® Windows operating systems, thedifferent releases of the Unix and Linux operating systems, any versionof the Mac OS® for Macintosh computers, any embedded operating system,any network operating system, any real-time operating system, any opensource operating system, any proprietary operating system, any operatingsystems for mobile computing devices or network devices, or any otheroperating system capable of running on the appliance 200 and performingthe operations described herein.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into what is referred to askernel or system space, and user or application space. The kernel spaceis typically reserved for running the kernel, including any devicedrivers, kernel extensions or other kernel related software. As known tothose skilled in the art, the kernel is the core of the operatingsystem, and provides access, control, and management of resources andhardware-related elements of the appliance 200. In accordance with anembodiment of the appliance 200, the kernel space also includes a numberof network services or processes working in conjunction with the networkoptimization engine 250, or any portion thereof. Additionally, theembodiment of the kernel will depend on the embodiment of the operatingsystem installed, configured, or otherwise used by the device 200. Incontrast to kernel space, user space is the memory area or portion ofthe operating system used by user mode applications or programsotherwise running in user mode. A user mode application may not accesskernel space directly and uses service calls in order to access kernelservices. The operating system uses the user or application space forexecuting or running applications and provisioning of user levelprograms, services, processes and/or tasks.

The appliance 200 has one or more network ports 266 for transmitting andreceiving data over a network 104. The network port 266 provides aphysical and/or logical interface between the computing device and anetwork 104 or another device 100 for transmitting and receiving networkcommunications. The type and form of network port 266 depends on thetype and form of network and type of medium for connecting to thenetwork. Furthermore, any software of, provisioned for or used by thenetwork port 266 and network stack 267 may run in either kernel space oruser space.

In one embodiment, the appliance 200 has one network stack 267, such asa TCP/IP based stack, for communicating on a network 105, such with theclient 102 and/or the server 106. In one embodiment, the network stack267 is used to communicate with a first network, such as network 104,and also with a second network 104′. In another embodiment, theappliance 200 has two or more network stacks, such as first networkstack 267A and a second network stack 267N. The first network stack 267Amay be used in conjunction with a first port 266A to communicate on afirst network 104. The second network stack 267N may be used inconjunction with a second port 266N to communicate on a second network104′. In one embodiment, the network stack(s) 267 has one or morebuffers for queuing one or more network packets for transmission by theappliance 200.

The network stack 267 includes any type and form of software, orhardware, or any combinations thereof, for providing connectivity to andcommunications with a network. In one embodiment, the network stack 267includes a software implementation for a network protocol suite. Thenetwork stack 267 may have one or more network layers, such as anynetworks layers of the Open Systems Interconnection (OSI) communicationsmodel as those skilled in the art recognize and appreciate. As such, thenetwork stack 267 may have any type and form of protocols for any of thefollowing layers of the OSI model: 1) physical link layer, 2) data linklayer, 3) network layer, 4) transport layer, 5) session layer, 6)presentation layer, and 7) application layer. In one embodiment, thenetwork stack 267 includes a transport control protocol (TCP) over thenetwork layer protocol of the internet protocol (IP), generally referredto as TCP/IP. In some embodiments, the TCP/IP protocol may be carriedover the Ethernet protocol, which may comprise any of the family of IEEEwide-area-network (WAN) or local-area-network (LAN) protocols, such asthose protocols covered by the IEEE 802.3. In some embodiments, thenetwork stack 267 has any type and form of a wireless protocol, such asIEEE 802.11 and/or mobile internet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 267 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 267, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 267 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 267 may be customized, modified or adapted to provide acustom or modified portion of the network stack 267 in support of any ofthe techniques described herein.

In one embodiment, the appliance 200 provides for or maintains atransport layer connection between a client 102 and server 106 using asingle network stack 267. In some embodiments, the appliance 200effectively terminates the transport layer connection by changing,managing or controlling the behavior of the transport control protocolconnection between the client and the server. In these embodiments, theappliance 200 may use a single network stack 267. In other embodiments,the appliance 200 terminates a first transport layer connection, such asa TCP connection of a client 102, and establishes a second transportlayer connection to a server 106 for use by or on behalf of the client102, e.g., the second transport layer connection is terminated at theappliance 200 and the server 106. The first and second transport layerconnections may be established via a single network stack 267. In otherembodiments, the appliance 200 may use multiple network stacks, forexample 267A and 267N. In these embodiments, the first transport layerconnection may be established or terminated at one network stack 267A,and the second transport layer connection may be established orterminated on the second network stack 267N. For example, one networkstack may be for receiving and transmitting network packets on a firstnetwork, and another network stack for receiving and transmittingnetwork packets on a second network.

As shown in FIG. 2A, the network optimization engine 250 includes one ormore of the following elements, components or modules: network packetprocessing engine 240, LAN/WAN detector 210, flow controller 220, QoSengine 236, protocol accelerator 234, compression engine 238, cachemanager 232 and policy engine 295′. The network optimization engine 250,or any portion thereof, may include software, hardware or anycombination of software and hardware. Furthermore, any software of,provisioned for or used by the network optimization engine 250 may runin either kernel space or user space. For example, in one embodiment,the network optimization engine 250 may run in kernel space. In anotherembodiment, the network optimization engine 250 may run in user space.In yet another embodiment, a first portion of the network optimizationengine 250 runs in kernel space while a second portion of the networkoptimization engine 250 runs in user space.

Network Packet Processing Engine

The network packet engine 240, also generally referred to as a packetprocessing engine or packet engine, is responsible for controlling andmanaging the processing of packets received and transmitted by appliance200 via network ports 266 and network stack(s) 267. The network packetengine 240 may operate at any layer of the network stack 267. In oneembodiment, the network packet engine 240 operates at layer 2 or layer 3of the network stack 267. In some embodiments, the packet engine 240intercepts or otherwise receives packets at the network layer, such asthe IP layer in a TCP/IP embodiment. In another embodiment, the packetengine 240 operates at layer 4 of the network stack 267. For example, insome embodiments, the packet engine 240 intercepts or otherwise receivespackets at the transport layer, such as intercepting packets as the TCPlayer in a TCP/IP embodiment. In other embodiments, the packet engine240 operates at any session or application layer above layer 4. Forexample, in one embodiment, the packet engine 240 intercepts orotherwise receives network packets above the transport layer protocollayer, such as the payload of a TCP packet in a TCP embodiment.

The packet engine 240 may include a buffer for queuing one or morenetwork packets during processing, such as for receipt of a networkpacket or transmission of a network packet. Additionally, the packetengine 240 is in communication with one or more network stacks 267 tosend and receive network packets via network ports 266. The packetengine 240 may include a packet processing timer. In one embodiment, thepacket processing timer provides one or more time intervals to triggerthe processing of incoming, i.e., received, or outgoing, i.e.,transmitted, network packets. In some embodiments, the packet engine 240processes network packets responsive to the timer. The packet processingtimer provides any type and form of signal to the packet engine 240 tonotify, trigger, or communicate a time related event, interval oroccurrence. In many embodiments, the packet processing timer operates inthe order of milliseconds, such as for example 100 ms, 50 ms, 25 ms, 10ms, 5 ms or 1 ms.

During operations, the packet engine 240 may be interfaced, integratedor be in communication with any portion of the network optimizationengine 250, such as the LAN/WAN detector 210, flow controller 220, QoSengine 236, protocol accelerator 234, compression engine 238, cachemanager 232 and/or policy engine 295′. As such, any of the logic,functions, or operations of the LAN/WAN detector 210, flow controller220, QoS engine 236, protocol accelerator 234, compression engine 238,cache manager 232 and policy engine 295′ may be performed responsive tothe packet processing timer and/or the packet engine 240. In someembodiments, any of the logic, functions, or operations of theencryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression logic 238 may be performed at the granularityof time intervals provided via the packet processing timer, for example,at a time interval of less than or equal to 10 ms. For example, in oneembodiment, the cache manager 232 may perform expiration of any cachedobjects responsive to the integrated packet engine 240 and/or the packetprocessing timer 242. In another embodiment, the expiry or invalidationtime of a cached object can be set to the same order of granularity asthe time interval of the packet processing timer, such as at every 10ms.

Cache Manager

The cache manager 232 may include software, hardware or any combinationof software and hardware to store data, information and objects to acache in memory or storage, provide cache access, and control and managethe cache. The data, objects or content processed and stored by thecache manager 232 may include data in any format, such as a markuplanguage, or any type of data communicated via any protocol. In someembodiments, the cache manager 232 duplicates original data storedelsewhere or data previously computed, generated or transmitted, inwhich the original data may require longer access time to fetch, computeor otherwise obtain relative to reading a cache memory or storageelement. Once the data is stored in the cache, future use can be made byaccessing the cached copy rather than re-fetching or re-computing theoriginal data, thereby reducing the access time. In some embodiments,the cache may comprise a data object in memory of the appliance 200. Inanother embodiment, the cache may comprise any type and form of storageelement of the appliance 200, such as a portion of a hard disk. In someembodiments, the processing unit of the device may provide cache memoryfor use by the cache manager 232. In yet further embodiments, the cachemanager 232 may use any portion and combination of memory, storage, orthe processing unit for caching data, objects, and other content.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any caching techniques of the appliance 200. Insome embodiments, the cache manager 232 may operate as an application,library, program, service, process, thread or task. In some embodiments,the cache manager 232 can comprise any type of general purpose processor(GPP), or any other type of integrated circuit, such as a FieldProgrammable Gate Array (FPGA), Programmable Logic Device (PLD), orApplication Specific Integrated Circuit (ASIC).

Policy Engine

The policy engine 295′ includes any logic, function or operations forproviding and applying one or more policies or rules to the function,operation or configuration of any portion of the appliance 200. Thepolicy engine 295′ may include, for example, an intelligent statisticalengine or other programmable application(s). In one embodiment, thepolicy engine 295 provides a configuration mechanism to allow a user toidentify, specify, define or configure a policy for the networkoptimization engine 250, or any portion thereof. For example, the policyengine 295 may provide policies for what data to cache, when to cachethe data, for whom to cache the data, when to expire an object in cacheor refresh the cache. In other embodiments, the policy engine 236 mayinclude any logic, rules, functions or operations to determine andprovide access, control and management of objects, data or content beingcached by the appliance 200 in addition to access, control andmanagement of security, network traffic, network access, compression orany other function or operation performed by the appliance 200.

In some embodiments, the policy engine 295′ provides and applies one ormore policies based on any one or more of the following: a user,identification of the client, identification of the server, the type ofconnection, the time of the connection, the type of network, or thecontents of the network traffic. In one embodiment, the policy engine295′ provides and applies a policy based on any field or header at anyprotocol layer of a network packet. In another embodiment, the policyengine 295′ provides and applies a policy based on any payload of anetwork packet. For example, in one embodiment, the policy engine 295′applies a policy based on identifying a certain portion of content of anapplication layer protocol carried as a payload of a transport layerpacket. In another example, the policy engine 295′ applies a policybased on any information identified by a client, server or usercertificate. In yet another embodiment, the policy engine 295′ applies apolicy based on any attributes or characteristics obtained about aclient 102, such as via any type and form of endpoint detection (see forexample the collection agent of the client agent discussed below).

In one embodiment, the policy engine 295′ works in conjunction orcooperation with the policy engine 295 of the application deliverysystem 290. In some embodiments, the policy engine 295′ is a distributedportion of the policy engine 295 of the application delivery system 290.In another embodiment, the policy engine 295 of the application deliverysystem 290 is deployed on or executed on the appliance 200. In someembodiments, the policy engines 295, 295′ both operate on the appliance200. In yet another embodiment, the policy engine 295′, or a portionthereof, of the appliance 200 operates on a server 106.

Multi-Protocol and Multi-Layer Compression Engine

The compression engine 238 includes any logic, business rules, functionor operations for compressing one or more protocols of a network packet,such as any of the protocols used by the network stack 267 of theappliance 200. The compression engine 238 may also be referred to as amulti-protocol compression engine 238 in that it may be designed,constructed or capable of compressing a plurality of protocols. In oneembodiment, the compression engine 238 applies context insensitivecompression, which is compression applied to data without knowledge ofthe type of data. In another embodiment, the compression engine 238applies context-sensitive compression. In this embodiment, thecompression engine 238 utilizes knowledge of the data type to select aspecific compression algorithm from a suite of suitable algorithms. Insome embodiments, knowledge of the specific protocol is used to performcontext-sensitive compression. In one embodiment, the appliance 200 orcompression engine 238 can use port numbers (e.g., well-known ports), aswell as data from the connection itself to determine the appropriatecompression algorithm to use. Some protocols use only a single type ofdata, requiring only a single compression algorithm that can be selectedwhen the connection is established. Other protocols contain differenttypes of data at different times. For example, POP, IMAP, SMTP, and HTTPall move files of arbitrary types interspersed with other protocol data.

In one embodiment, the compression engine 238 uses a delta-typecompression algorithm. In another embodiment, the compression engine 238uses first site compression as well as searching for repeated patternsamong data stored in cache, memory or disk. In some embodiments, thecompression engine 238 uses a lossless compression algorithm. In otherembodiments, the compression engine uses a lossy compression algorithm.In some cases, knowledge of the data type and, sometimes, permissionfrom the user are required to use a lossy compression algorithm.Compression is not limited to the protocol payload. The control fieldsof the protocol itself may be compressed. In some embodiments, thecompression engine 238 uses a different algorithm than that used for thepayload.

In some embodiments, the compression engine 238 compresses at one ormore layers of the network stack 267. In one embodiment, the compressionengine 238 compresses at a transport layer protocol. In anotherembodiment, the compression engine 238 compresses at an applicationlayer protocol. In some embodiments, the compression engine 238compresses at a layer 2-4 protocol. In other embodiments, thecompression engine 238 compresses at a layer 5-7 protocol. In yetanother embodiment, the compression engine compresses a transport layerprotocol and an application layer protocol. In some embodiments, thecompression engine 238 compresses a layer 2-4 protocol and a layer 5-7protocol.

In some embodiments, the compression engine 238 uses memory-basedcompression, cache-based compression or disk-based compression or anycombination thereof. As such, the compression engine 238 may be referredto as a multi-layer compression engine. In one embodiment, thecompression engine 238 uses a history of data stored in memory, such asRAM. In another embodiment, the compression engine 238 uses a history ofdata stored in a cache, such as L2 cache of the processor. In otherembodiments, the compression engine 238 uses a history of data stored toa disk or storage location. In some embodiments, the compression engine238 uses a hierarchy of cache-based, memory-based and disk-based datahistory. The compression engine 238 may first use the cache-based datato determine one or more data matches for compression, and then maycheck the memory-based data to determine one or more data matches forcompression. In another case, the compression engine 238 may check diskstorage for data matches for compression after checking either thecache-based and/or memory-based data history.

In one embodiment, multi-protocol compression engine 238 compressesbi-directionally between clients 102 a-102 n and servers 106 a-106 n anyTCP/IP based protocol, including Messaging Application ProgrammingInterface (MAPI) (email), File Transfer Protocol (FTP), HyperTextTransfer Protocol (HTTP), Common Internet File System (CIFS) protocol(file transfer), Independent Computing Architecture (ICA) protocol,Remote Desktop Protocol (RDP), Wireless Application Protocol (WAP),Mobile IP protocol, and Voice Over IP (VoIP) protocol. In otherembodiments, multi-protocol compression engine 238 provides compressionof HyperText Markup Language (HTML) based protocols and in someembodiments, provides compression of any markup languages, such as theExtensible Markup Language (XML). In one embodiment, the multi-protocolcompression engine 238 provides compression of any high-performanceprotocol, such as any protocol designed for appliance 200 to appliance200 communications. In another embodiment, the multi-protocolcompression engine 238 compresses any payload of or any communicationusing a modified transport control protocol, such as Transaction TCP(T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP with largewindows (TCP-LW), a congestion prediction protocol such as the TCP-Vegasprotocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, SAP and Siebel, and evenmobile clients, such as the Pocket PC. In some embodiments, themulti-protocol compression engine by integrating with packet processingengine 240 accessing the network stack 267 is able to compress any ofthe protocols carried by a transport layer protocol, such as anyapplication layer protocol.

LAN/WAN Detector

The LAN/WAN detector 238 includes any logic, business rules, function oroperations for automatically detecting a slow side connection (e.g., awide area network (WAN) connection such as an Intranet) and associatedport 267, and a fast side connection (e.g., a local area network (LAN)connection) and an associated port 267. In some embodiments, the LAN/WANdetector 238 monitors network traffic on the network ports 267 of theappliance 200 to detect a synchronization packet, sometimes referred toas a “tagged” network packet. The synchronization packet identifies atype or speed of the network traffic. In one embodiment, thesynchronization packet identifies a WAN speed or WAN type connection.The LAN/WAN detector 238 also identifies receipt of an acknowledgementpacket to a tagged synchronization packet and on which port it isreceived. The appliance 200 then configures itself to operate theidentified port on which the tagged synchronization packet arrived sothat the speed on that port is set to be the speed associated with thenetwork connected to that port. The other port is then set to the speedassociated with the network connected to that port.

For ease of discussion herein, reference to “fast” side will be madewith respect to connection with a wide area network (WAN), e.g., theInternet, and operating at a network speed of the WAN. Likewise,reference to “slow” side will be made with respect to connection with alocal area network (LAN) and operating at a network speed the LAN.However, it is noted that “fast” and “slow” sides in a network canchange on a per-connection basis and are relative terms to the speed ofthe network connections or to the type of network topology. Suchconfigurations are useful in complex network topologies, where a networkis “fast” or “slow” only when compared to adjacent networks and not inany absolute sense.

In one embodiment, the LAN/WAN detector 238 may be used to allow forauto-discovery by an appliance 200 of a network to which it connects. Inanother embodiment, the LAN/WAN detector 238 may be used to detect theexistence or presence of a second appliance 200′ deployed in the network104. For example, an auto-discovery mechanism in operation in accordancewith FIG. 1A functions as follows: appliance 200 and 200′ are placed inline with the connection linking client 102 and server 106. Theappliances 200 and 200′ are at the ends of a low-speed link, e.g.,Internet, connecting two LANs. In one example embodiment, appliances 200and 200′ each include two ports—one to connect with the “lower” speedlink and the other to connect with a “higher” speed link, e.g., a LAN.Any packet arriving at one port is copied to the other port. Thus,appliance 200 and 200′ are each configured to function as a bridgebetween the two networks 104.

When an end node, such as the client 102, opens a new TCP connectionwith another end node, such as the server 106, the client 102 sends aTCP packet with a synchronization (SYN) header bit set, or a SYN packet,to the server 106. In the present example, client 102 opens a transportlayer connection to server 106. When the SYN packet passes throughappliance 200, the appliance 200 inserts, attaches or otherwise providesa characteristic TCP header option to the packet, which announces itspresence. If the packet passes through a second appliance, in thisexample appliance 200′ the second appliance notes the header option onthe SYN packet. The server 106 responds to the SYN packet with asynchronization acknowledgment (SYN-ACK) packet. When the SYN-ACK packetpasses through appliance 200′, a TCP header option is tagged (e.g.,attached, inserted or added) to the SYN-ACK packet to announce appliance200′ presence to appliance 200. When appliance 200 receives this packet,both appliances 200, 200′ are now aware of each other and the connectioncan be appropriately accelerated.

Further to the operations of the LAN/WAN detector 238, a method orprocess for detecting “fast” and “slow” sides of a network using a SYNpacket is described. During a transport layer connection establishmentbetween a client 102 and a server 106, the appliance 200 via the LAN/WANdetector 238 determines whether the SYN packet is tagged with anacknowledgement (ACK). If it is tagged, the appliance 200 identifies orconfigures the port receiving the tagged SYN packet (SYN-ACK) as the“slow” side. In one embodiment, the appliance 200 optionally removes theACK tag from the packet before copying the packet to the other port. Ifthe LAN/WAN detector 238 determines that the packet is not tagged, theappliance 200 identifies or configure the port receiving the untaggedpacket as the “fast” side. The appliance 200 then tags the SYN packetwith an ACK and copies the packet to the other port.

In another embodiment, the LAN/WAN detector 238 detects fast and slowsides of a network using a SYN-ACK packet. The appliance 200 via theLAN/WAN detector 238 determines whether the SYN-ACK packet is taggedwith an acknowledgement (ACK). If it is tagged, the appliance 200identifies or configures the port receiving the tagged SYN packet(SYN-ACK) as the “slow” side. In one embodiment, the appliance 200optionally removes the ACK tag from the packet before copying the packetto the other port. If the LAN/WAN detector 238 determines that thepacket is not tagged, the appliance 200 identifies or configures theport receiving the untagged packet as the “fast” side. The LAN/WANdetector 238 determines whether the SYN packet was tagged. If the SYNpacket was not tagged, the appliance 200 copied the packet to the otherport. If the SYN packet was tagged, the appliance tags the SYN-ACKpacket before copying it to the other port.

The appliance 200, 200′ may add, insert, modify, attach or otherwiseprovide any information or data in the TCP option header to provide anyinformation, data or characteristics about the network connection,network traffic flow, or the configuration or operation of the appliance200. In this manner, not only does an appliance 200 announce itspresence to another appliance 200′ or tag a higher or lower speedconnection, the appliance 200 provides additional information and datavia the TCP option headers about the appliance or the connection. TheTCP option header information may be useful to or used by an appliancein controlling, managing, optimizing, acceleration or improving thenetwork traffic flow traversing the appliance 200, or to otherwiseconfigure itself or operation of a network port.

Although generally described in conjunction with detecting speeds ofnetwork connections or the presence of appliances, the LAN/WAN detector238 can be used for applying any type of function, logic or operation ofthe appliance 200 to a port, connection or flow of network traffic. Inparticular, automated assignment of ports can occur whenever a deviceperforms different functions on different ports, where the assignment ofa port to a task can be made during the unit's operation, and/or thenature of the network segment on each port is discoverable by theappliance 200.

Flow Control

The flow controller 220 includes any logic, business rules, logicalrules, functions or operations for optimizing, accelerating or otherwiseimproving the performance, operation or quality of service of transportlayer communications of network packets or the delivery of packets atthe transport layer. A flow controller, also sometimes referred to as aflow control module, regulates, manages and controls data transferrates. In some embodiments, the flow controller 220 is deployed at orconnected at a bandwidth bottleneck in the network 104. In oneembodiment, the flow controller 220 effectively regulates, manages andcontrols bandwidth usage or utilization. In other embodiments, the flowcontrol modules may also be deployed at points on the network of latencytransitions (low latency to high latency) and on links with media losses(such as wireless or satellite links).

In some embodiments, a flow controller 220 may include a receiver-sideflow control module for controlling the rate of receipt of networktransmissions and a sender-side flow control module for the controllingthe rate of transmissions of network packets. In other embodiments, afirst flow controller 220 includes a receiver-side flow control moduleand a second flow controller 220′ includes a sender-side flow controlmodule. In some embodiments, a first flow controller 220 is deployed ona first appliance 200 and a second flow controller 220′ is deployed on asecond appliance 200′. As such, in some embodiments, a first appliance200 controls the flow of data on the receiver side and a secondappliance 200′ controls the data flow from the sender side. In yetanother embodiment, a single appliance 200 includes flow control forboth the receiver-side and sender-side of network communicationstraversing the appliance 200.

In one embodiment, a flow control module 220 is configured to allowbandwidth at the bottleneck to be more fully utilized, and in someembodiments, not overutilized. In some embodiments, the flow controlmodule 220 transparently buffers (or rebuffers data already buffered by,for example, the sender) network sessions that pass between nodes havingassociated flow control modules 220. When a session passes through twoor more flow control modules 220, one or more of the flow controlmodules controls a rate of the session(s).

In one embodiment, the flow control module 200 is configured withpredetermined data relating to bottleneck bandwidth. In anotherembodiment, the flow control module 220 may be configured to detect thebottleneck bandwidth or data associated therewith. Unlike conventionalnetwork protocols such as TCP, a receiver-side flow control module 220controls the data transmission rate. The receiver-side flow controlmodule controls 220 the sender-side flow control module, e.g., 220, datatransmission rate by forwarding transmission rate limits to thesender-side flow control module 220. In one embodiment, thereceiver-side flow control module 220 piggybacks these transmission ratelimits on acknowledgement (ACK) packets (or signals) sent to the sender,e.g., client 102, by the receiver, e.g., server 106. The receiver-sideflow control module 220 does this in response to rate control requeststhat are sent by the sender side flow control module 220′. The requestsfrom the sender-side flow control module 220′ may be “piggybacked” ondata packets sent by the sender 106.

In some embodiments, the flow controller 220 manipulates, adjusts,simulates, changes, improves or otherwise adapts the behavior of thetransport layer protocol or any other layer protocol to provide improvedperformance or operations of delivery, data rates and/or bandwidthutilization of the transport layer. The flow controller 220 mayimplement a plurality of data flow control techniques at the transportlayer, including but not limited to 1) pre-acknowledgements, 2) windowvirtualization, 3) recongestion techniques, 3) local retransmissiontechniques, 4) wavefront detection and disambiguation, 5) transportcontrol protocol selective acknowledgements, 6) transaction boundarydetection techniques and 7) repacketization.

Although a sender may be generally described herein as a client 102 anda receiver as a server 106, a sender may be any end point such as aserver 106 or any computing device 100 on the network 104. Likewise, areceiver may be a client 102 or any other computing device on thenetwork 104.

Pre-Acknowledgements

In brief overview of a pre-acknowledgement flow control technique, theflow controller 220, in some embodiments, handles the acknowledgementsand retransmits for a sender, effectively terminating the sender'sconnection with the downstream portion of a network connection. Inreference to FIG. 1B, one possible deployment of an appliance 200 into anetwork architecture to implement this feature is depicted. In thisexample environment, a sending computer or client 102 transmits data onnetwork 104, for example, via a switch, which determines that the datais destined for VPN appliance 205. Because of the chosen networktopology, all data destined for VPN appliance 205 traverses appliance200, so the appliance 200 can apply any necessary algorithms to thisdata.

Continuing further with the example, the client 102 transmits a packet,which is received by the appliance 200. When the appliance 200 receivesthe packet, which is transmitted from the client 102 to a recipient viathe VPN appliance 205 the appliance 200 retains a copy of the packet andforwards the packet downstream to the VPN appliance 205. The appliance200 then generates an acknowledgement packet (ACK) and sends the ACKpacket back to the client 102 or sending endpoint. This ACK, apre-acknowledgment, causes the sender 102 to believe that the packet hasbeen delivered successfully, freeing the sender's resources forsubsequent processing. The appliance 200 retains the copy of the packetdata in the event that a retransmission of the packet is required, sothat the sender 102 does not have to handle retransmissions of the data.This early generation of acknowledgements may be called “preacking”

If a retransmission of the packet is required, the appliance 200retransmits the packet to the sender. The appliance 200 may determinewhether retransmission is required as a sender would in a traditionalsystem, for example, determining that a packet is lost if anacknowledgement has not been received for the packet after apredetermined amount of time. To this end, the appliance 200 monitorsacknowledgements generated by the receiving endpoint, e.g., server 106(or any other downstream network entity) so that it can determinewhether the packet has been successfully delivered or needs to beretransmitted. If the appliance 200 determines that the packet has beensuccessfully delivered, the appliance 200 is free to discard the savedpacket data. The appliance 200 may also inhibit forwardingacknowledgements for packets that have already been received by thesending endpoint.

In the embodiment described above, the appliance 200 via the flowcontroller 220 controls the sender 102 through the delivery ofpre-acknowledgements, also referred to as “preacks”, as though theappliance 200 was a receiving endpoint itself. Since the appliance 200is not an endpoint and does not actually consume the data, the appliance200 includes a mechanism for providing overflow control to the sendingendpoint. Without overflow control, the appliance 200 could run out ofmemory because the appliance 200 stores packets that have been preackedto the sending endpoint but not yet acknowledged as received by thereceiving endpoint. Therefore, in a situation in which the sender 102transmits packets to the appliance 200 faster than the appliance 200 canforward the packets downstream, the memory available in the appliance200 to store unacknowledged packet data can quickly fill. A mechanismfor overflow control allows the appliance 200 to control transmission ofthe packets from the sender 102 to avoid this problem.

In one embodiment, the appliance 200 or flow controller 220 includes aninherent “self-clocking” overflow control mechanism. This self-clockingis due to the order in which the appliance 200 may be designed totransmit packets downstream and send ACKs to the sender 102 or 106. Insome embodiments, the appliance 200 does not preack the packet untilafter it transmits the packet downstream. In this way, the sender 102will receive the ACKs at the rate at which the appliance 200 is able totransmit packets rather than the rate at which the appliance 200receives packets from the sender 100. This helps to regulate thetransmission of packets from a sender 102.

Window Virtualization

Another overflow control mechanism that the appliance 200 may implementis to use the TCP window size parameter, which tells a sender how muchbuffer the receiver is permitting the sender to fill up. A nonzerowindow size (e.g., a size of at least one Maximum Segment Size (MSS)) ina preack permits the sending endpoint to continue to deliver data to theappliance, whereas a zero window size inhibits further datatransmission. Accordingly, the appliance 200 may regulate the flow ofpackets from the sender, for example when the appliance's 200 buffer isbecoming full, by appropriately setting the TCP window size in eachpreack.

Another technique to reduce this additional overhead is to applyhysteresis. When the appliance 200 delivers data to the slower side, theoverflow control mechanism in the appliance 200 can require that aminimum amount of space be available before sending a nonzero windowadvertisement to the sender. In one embodiment, the appliance 200 waitsuntil there is a minimum of a predetermined number of packets, such asfour packets, of space available before sending a nonzero window packet,such as a window size of four packet). This reduces the overhead byapproximately a factor four, since only two ACK packets are sent foreach group of four data packets, instead of eight ACK packets for fourdata packets.

Another technique the appliance 200 or flow controller 220 may use foroverflow control is the TCP delayed ACK mechanism, which skips ACKs toreduce network traffic. The TCP delayed ACKs automatically delay thesending of an ACK, either until two packets are received or until afixed timeout has occurred. This mechanism alone can result in cuttingthe overhead in half; moreover, by increasing the numbers of packetsabove two, additional overhead reduction is realized. But merelydelaying the ACK itself may be insufficient to control overflow, and theappliance 200 may also use the advertised window mechanism on the ACKsto control the sender. When doing this, the appliance 200 in oneembodiment avoids triggering the timeout mechanism of the sender bydelaying the ACK too long.

In one embodiment, the flow controller 220 does not preack the lastpacket of a group of packets. By not preacking the last packet, or atleast one of the packets in the group, the appliance avoids a falseacknowledgement for a group of packets. For example, if the appliancewere to send a preack for a last packet and the packet were subsequentlylost, the sender would have been tricked into thinking that the packetis delivered when it was not. Thinking that the packet had beendelivered, the sender could discard that data. If the appliance alsolost the packet, there would be no way to retransmit the packet to therecipient. By not preacking the last packet of a group of packets, thesender will not discard the packet until it has been delivered.

In another embodiment, the flow controller 220 may use a windowvirtualization technique to control the rate of flow or bandwidthutilization of a network connection. Though it may not immediately beapparent from examining conventional literature such as RFC 1323, thereis effectively a send window for transport layer protocols such as TCP.The send window is similar to the receive window, in that it consumesbuffer space (though on the sender). The sender's send window consistsof all data sent by the application that has not been acknowledged bythe receiver. This data must be retained in memory in caseretransmission is required. Since memory is a shared resource, some TCPstack implementations limit the size of this data. When the send windowis full, an attempt by an application program to send more data resultsin blocking the application program until space is available. Subsequentreception of acknowledgements will free send-window memory and unblockthe application program. In some embodiments, this window size is knownas the socket buffer size in some TCP implementations.

In one embodiment, the flow control module 220 is configured to provideaccess to increased window (or buffer) sizes. This configuration mayalso be referenced to as window virtualization. In the embodiment of TCPas the transport layer protocol, the TCP header includes a bit stringcorresponding to a window scale. In one embodiment, “window” may bereferenced in a context of send, receive, or both.

One embodiment of window virtualization is to insert a preackingappliance 200 into a TCP session. In reference to any of theenvironments of FIG. 1A or 1B, initiation of a data communicationsession between a source node, e.g., client 102 (for ease of discussion,now referenced as source node 102), and a destination node, e.g., server106 (for ease of discussion, now referenced as destination node 106) isestablished. For TCP communications, the source node 102 initiallytransmits a synchronization signal (“SYN”) through its local areanetwork 104 to first flow control module 220. The first flow controlmodule 220 inserts a configuration identifier into the TCP headeroptions area. The configuration identifier identifies this point in thedata path as a flow control module.

The appliances 200 via a flow control module 220 provide window (orbuffer) to allow increasing data buffering capabilities within a sessiondespite having end nodes with small buffer sizes, e.g., typically 16 kbytes. However, RFC 1323 requires window scaling for any buffer sizesgreater than 64 k bytes, which must be set at the time of sessioninitialization (SYN, SYN-ACK signals). Moreover, the window scalingcorresponds to the lowest common denominator in the data path, often anend node with small buffer size. This window scale often is a scale of 0or 1, which corresponds to a buffer size of up to 64 k or 128 k bytes.Note that because the window size is defined as the window field in eachpacket shifted over by the window scale, the window scale establishes anupper limit for the buffer, but does not guarantee the buffer isactually that large. Each packet indicates the current available bufferspace at the receiver in the window field.

In one embodiment of scaling using the window virtualization technique,during connection establishment (i.e., initialization of a session) whenthe first flow control module 220 receives from the source node 102 theSYN signal (or packet), the flow control module 220 stores the windowsscale of the source node 102 (which is the previous node) or stores a 0for window scale if the scale of the previous node is missing. The firstflow control module 220 also modifies the scale, e.g., increases thescale to 4 from 0 or 1, in the SYN-FCM signal. When the second flowcontrol module 220 receives the SYN signal, it stores the increasedscale from the first flow control signal and resets the scale in the SYNsignal back to the source node 103 scale value for transmission to thedestination node 106. When the second flow controller 220 receives theSYN-ACK signal from the destination node 106, it stores the scale fromthe destination node 106 scale, e.g., 0 or 1, and modifies it to anincreased scale that is sent with the SYN-ACK-FCM signal. The first flowcontrol node 220 receives and notes the received window scale andrevises the windows scale sent back to the source node 102 back down tothe original scale, e.g., 0 or 1. Based on the above window shiftconversation during connection establishment, the window field in everysubsequent packet, e.g., TCP packet, of the session must be shiftedaccording to the window shift conversion.

The window scale, as described above, expresses buffer sizes of over 64k and may not be required for window virtualization. Thus, shifts forwindow scale may be used to express increased buffer capacity in eachflow control module 220. This increase in buffer capacity in may bereferenced as window (or buffer) virtualization. The increase in buffersize allows greater packet through put from and to the respective endnodes 102 and 106. Note that buffer sizes in TCP are typically expressedin terms of bytes, but for ease of discussion “packets” may be used inthe description herein as it relates to virtualization.

By way of example, a window (or buffer) virtualization performed by theflow controller 220 is described. In this example, the source node 102and the destination node 106 are configured similar to conventional endnodes having a limited buffer capacity of 16 k bytes, which equalsapproximately 10 packets of data. Typically, an end node 102, 106 mustwait until the packet is transmitted and confirmation is received beforea next group of packets can be transmitted. In one embodiment, usingincreased buffer capacity in the flow control modules 220, when thesource node 103 transmits its data packets, the first flow controlmodule 220 receives the packets, stores it in its larger capacitybuffer, e.g., 512 packet capacity, and immediately sends back anacknowledgement signal indicating receipt of the packets (“REC-ACK”)back to the source node 102. The source node 102 can then “flush” itscurrent buffer, load it with 10 new data packets, and transmit thoseonto the first flow control module 220. Again, the first flow controlmodule 220 transmits a REC-ACK signal back to the source node 102 andthe source node 102 flushes its buffer and loads it with 10 more newpackets for transmission.

As the first flow control module 220 receives the data packets from thesource nodes, it loads up its buffer accordingly. When it is ready thefirst flow control module 220 can begin transmitting the data packets tothe second flow control module 230, which also has an increased buffersize, for example, to receive 512 packets. The second flow controlmodule 220′ receives the data packets and begins to transmit 10 packetsat a time to the destination node 106. Each REC-ACK received at thesecond flow control node 220 from the destination node 106 results in 10more packets being transmitted to the destination node 106 until all thedata packets are transferred. Hence, the present disclosure is able toincrease data transmission throughput between the source node (sender)102 and the destination node (receiver) 106 by taking advantage of thelarger buffer in the flow control modules 220, 220′ between the devices.

It is noted that by “preacking” the transmission of data as describedpreviously, a sender (or source node 102) is allowed to transmit moredata than is possible without the preacks, thus affecting a largerwindow size. For example, in one embodiment this technique is effectivewhen the flow control module 220, 220′ is located “near” a node (e.g.,source node 102 or destination node 106) that lacks large windows.

Recongestion

Another technique or algorithm of the flow controller 220 is referred toas recongestion. The standard TCP congestion avoidance algorithms areknown to perform poorly in the face of certain network conditions,including: large RTTs (round trip times), high packet loss rates, andothers. When the appliance 200 detects a congestion condition such aslong round trip times or high packet loss, the appliance 200 intervenes,substituting an alternate congestion avoidance algorithm that bettersuits the particular network condition. In one embodiment, therecongestion algorithm uses preacks to effectively terminate theconnection between the sender and the receiver. The appliance 200 thenresends the packets from itself to the receiver, using a differentcongestion avoidance algorithm. Recongestion algorithms may be dependenton the characteristics of the TCP connection. The appliance 200 monitorseach TCP connection, characterizing it with respect to the differentdimensions, selecting a recongestion algorithm that is appropriate forthe current characterization.

In one embodiment, upon detecting a TCP connection that is limited byround trip times (RTT), a recongestion algorithm is applied whichbehaves as multiple TCP connections. Each TCP connection operates withinits own performance limit but the aggregate bandwidth achieves a higherperformance level. One parameter in this mechanism is the number ofparallel connections that are applied (N). Too large a value of N andthe connection bundle achieves more than its fair share of bandwidth.Too small a value of N and the connection bundle achieves less than itsfair share of bandwidth. One method of establishing “N” relies on theappliance 200 monitoring the packet loss rate, RTT, and packet size ofthe actual connection. These numbers are plugged into a TCP responsecurve formula to provide an upper limit on the performance of a singleTCP connection in the present configuration. If each connection withinthe connection bundle is achieving substantially the same performance asthat computed to be the upper limit, then additional parallelconnections are applied. If the current bundle is achieving lessperformance than the upper limit, the number of parallel connections isreduced. In this manner, the overall fairness of the system ismaintained since individual connection bundles contain no moreparallelism than is required to eliminate the restrictions imposed bythe protocol itself. Furthermore, each individual connection retains TCPcompliance.

Another method of establishing “N” is to utilize a parallel flow controlalgorithm such as the TCP “Vegas” algorithm or its improved version“Stabilized Vegas.” In this method, the network information associatedwith the connections in the connection bundle (e.g., RTT, loss rate,average packet size, etc.) is aggregated and applied to the alternateflow control algorithm. The results of this algorithm are in turndistributed among the connections of the bundle controlling their number(i.e., N). Optionally, each connection within the bundle continues usingthe standard TCP congestion avoidance algorithm.

In another embodiment, the individual connections within a parallelbundle are virtualized, i.e., actual individual TCP connections are notestablished. Instead the congestion avoidance algorithm is modified tobehave as though there were N parallel connections. This method has theadvantage of appearing to transiting network nodes as a singleconnection. Thus the QOS, security and other monitoring methods of thesenodes are unaffected by the recongestion algorithm. In yet anotherembodiment, the individual connections within a parallel bundle arereal, i.e., a separate. TCP connection is established for each of theparallel connections within a bundle. The congestion avoidance algorithmfor each TCP connection need not be modified.

Retransmission

In some embodiments, the flow controller 220 may apply a localretransmission technique. One reason for implementing preacks is toprepare to transit a high-loss link (e.g., wireless). In theseembodiments, the preacking appliance 200 or flow control module 220 islocated most beneficially “before” the wireless link. This allowsretransmissions to be performed closer to the high loss link, removingthe retransmission burden from the remainder of the network. Theappliance 200 may provide local retransmission, in which case, packetsdropped due to failures of the link are retransmitted directly by theappliance 200. This is advantageous because it eliminates theretransmission burden upon an end node, such as server 106, andinfrastructure of any of the networks 104. With appliance 200 providinglocal retransmissions, the dropped packet can be retransmitted acrossthe high loss link without necessitating a retransmit by an end node anda corresponding decrease in the rate of data transmission from the endnode.

Another reason for implementing preacks is to avoid a receive time out(RTO) penalty. In standard TCP there are many situations that result inan RTO, even though a large percentage of the packets in flight weresuccessfully received. With standard TCP algorithms, dropping more thanone packet within an RTT window would likely result in a timeout.Additionally, most TCP connections experience a timeout if aretransmitted packet is dropped. In a network with a high bandwidthdelay product, even a relatively small packet loss rate will causefrequent Retransmission timeouts (RTOs). In one embodiment, theappliance 200 uses a retransmit and timeout algorithm is avoid prematureRTOs. The appliance 200 or flow controller 220 maintains a count ofretransmissions is maintained on a per-packet basis. Each time that apacket is retransmitted, the count is incremented by one and theappliance 200 continues to transmit packets. In some embodiments, onlyif a packet has been retransmitted a predetermined number of times is anRTO declared.

Wavefront Detection and Disambiguation

In some embodiments, the appliance 200 or flow controller 220 useswavefront detection and disambiguation techniques in managing andcontrolling flow of network traffic. In this technique, the flowcontroller 220 uses transmit identifiers or numbers to determine whetherparticular data packets need to be retransmitted. By way of example, asender transmits data packets over a network, where each instance of atransmitted data packet is associated with a transmit number. It can beappreciated that the transmit number for a packet is not the same as thepacket's sequence number, since a sequence number references the data inthe packet while the transmit number references an instance of atransmission of that data. The transmit number can be any informationusable for this purpose, including a timestamp associated with a packetor simply an increasing number (similar to a sequence number or a packetnumber). Because a data segment may be retransmitted, different transmitnumbers may be associated with a particular sequence number.

As the sender transmits data packets, the sender maintains a datastructure of acknowledged instances of data packet transmissions. Eachinstance of a data packet transmission is referenced by its sequencenumber and transmit number. By maintaining a transmit number for eachpacket, the sender retains the ordering of the transmission of datapackets. When the sender receives an ACK or a SACK, the senderdetermines the highest transmit number associated with packets that thereceiver indicated has arrived (in the received acknowledgement). Anyoutstanding unacknowledged packets with lower transmit numbers arepresumed lost.

In some embodiments, the sender is presented with an ambiguous situationwhen the arriving packet has been retransmitted: a standard ACK/SACKdoes not contain enough information to allow the sender to determinewhich transmission of the arriving packet has triggered theacknowledgement. After receiving an ambiguous acknowledgement,therefore, the sender disambiguates the acknowledgement to associate itwith a transmit number. In various embodiments, one or a combination ofseveral techniques may be used to resolve this ambiguity.

In one embodiment, the sender includes an identifier with a transmitteddata packet, and the receiver returns that identifier or a functionthereof with the acknowledgement. The identifier may be a timestamp(e.g., a TCP timestamp as described in RFC 1323), a sequential number,or any other information that can be used to resolve between two or moreinstances of a packet's transmission. In an embodiment in which the TCPtimestamp option is used to disambiguate the acknowledgement, eachpacket is tagged with up to 32-bits of unique information. Upon receiptof the data packet, the receiver echoes this unique information back tothe sender with the acknowledgement. The sender ensures that theoriginally sent packet and its retransmitted version or versions containdifferent values for the timestamp option, allowing it to unambiguouslyeliminate the ACK ambiguity. The sender may maintain this uniqueinformation, for example, in the data structure in which it stores thestatus of sent data packets. This technique is advantageous because itcomplies with industry standards and is thus likely to encounter littleor no interoperability issues. However, this technique may require tenbytes of TCP header space in some implementations, reducing theeffective throughput rate on the network and reducing space availablefor other TCP options.

In another embodiment, another field in the packet, such as the IP IDfield, is used to disambiguate in a way similar to the TCP timestampoption described above. The sender arranges for the ID field values ofthe original and the retransmitted version or versions of the packet tohave different ID fields in the IP header. Upon reception of the datapacket at the receiver, or a proxy device thereof, the receiver sets theID field of the ACK packet to a function of the ID field of the packetthat triggers the ACK. This method is advantageous, as it requires noadditional data to be sent, preserving the efficiency of the network andTCP header space. The function chosen should provide a high degree oflikelihood of providing disambiguation. In a preferred embodiment, thesender selects IP ID values with the most significant bit set to 0. Whenthe receiver responds, the IP ID value is set to the same IP ID valuewith the most significant bit set to a one.

In another embodiment, the transmit numbers associated withnon-ambiguous acknowledgements are used to disambiguate an ambiguousacknowledgement. This technique is based on the principle thatacknowledgements for two packets will tend to be received closer in timeas the packets are transmitted closer in time. Packets that are notretransmitted will not result in ambiguity, as the acknowledgementsreceived for such packets can be readily associated with a transmitnumber. Therefore, these known transmit numbers are compared to thepossible transmit numbers for an ambiguous acknowledgement received nearin time to the known acknowledgement. The sender compares the transmitnumbers of the ambiguous acknowledgement against the last known receivedtransmit number, selecting the one closest to the known receivedtransmit number. For example, if an acknowledgement for data packet 1 isreceived and the last received acknowledgement was for data packet 5,the sender resolves the ambiguity by assuming that the third instance ofdata packet 1 caused the acknowledgement.

Selective Acknowledgements

Another technique of the appliance 200 or flow controller 220 is toimplement an embodiment of transport control protocol selectiveacknowledgements, or TCP SACK, to determine what packets have or havenot been received. This technique allows the sender to determineunambiguously a list of packets that have been received by the receiveras well as an accurate list of packets not received. This functionalitymay be implemented by modifying the sender and/or receiver, or byinserting sender- and receiver-side flow control modules 220 in thenetwork path between the sender and receiver. In reference to FIG. 1A orFIG. 1B, a sender, e.g., client 102, is configured to transmit datapackets to the receiver, e.g., server 106, over the network 104. Inresponse, the receiver returns a TCP Selective Acknowledgment option,referred to as SACK packet to the sender. In one embodiment, thecommunication is bi-directional, although only one direction ofcommunication is discussed here for simplicity. The receiver maintains alist, or other suitable data structure, that contains a group of rangesof sequence numbers for data packets that the receiver has actuallyreceived. In some embodiments, the list is sorted by sequence number inan ascending or descending order. The receiver also maintains a left-offpointer, which comprises a reference into the list and indicates theleft-off point from the previously generated SACK packet.

Upon reception of a data packet, the receiver generates and transmits aSACK packet back to the sender. In some embodiments, the SACK packetincludes a number of fields, each of which can hold a range of sequencenumbers to indicate a set of received data packets. The receiver fillsthis first field of the SACK packet with a range of sequence numbersthat includes the landing packet that triggered the SACK packet. Theremaining available SACK fields are filled with ranges of sequencenumbers from the list of received packets. As there are more ranges inthe list than can be loaded into the SACK packet, the receiver uses theleft-off pointer to determine which ranges are loaded into the SACKpacket. The receiver inserts the SACK ranges consecutively from thesorted list, starting from the range referenced by the pointer andcontinuing down the list until the available SACK range space in the TCPheader of the SACK packet is consumed. The receiver wraps around to thestart of the list if it reaches the end. In some embodiments, two orthree additional SACK ranges can be added to the SACK range information.

Once the receiver generates the SACK packet, the receiver sends theacknowledgement back to the sender. The receiver then advances theleft-off pointer by one or more SACK range entries in the list. If thereceiver inserts four SACK ranges, for example, the left-off pointer maybe advanced two SACK ranges in the list. When the advanced left-offpointer reaches at the end of the list, the pointer is reset to thestart of the list, effectively wrapping around the list of knownreceived ranges. Wrapping around the list enables the system to performwell, even in the presence of large losses of SACK packets, since theSACK information that is not communicated due to a lost SACK packet willeventually be communicated once the list is wrapped around.

It can be appreciated, therefore, that a SACK packet may communicateseveral details about the condition of the receiver. First, the SACKpacket indicates that, upon generation of the SACK packet, the receiverhad just received a data packet that is within the first field of theSACK information. Secondly, the second and subsequent fields of the SACKinformation indicate that the receiver has received the data packetswithin those ranges. The SACK information also implies that the receiverhad not, at the time of the SACK packet's generation, received any ofthe data packets that fall between the second and subsequent fields ofthe SACK information. In essence, the ranges between the second andsubsequent ranges in the SACK information are “holes” in the receiveddata, the data therein known not to have been delivered. Using thismethod, therefore, when a SACK packet has sufficient space to includemore than two SACK ranges, the receiver may indicate to the sender arange of data packets that have not yet been received by the receiver.

In another embodiment, the sender uses the SACK packet described abovein combination with the retransmit technique described above to makeassumptions about which data packets have been delivered to thereceiver. For example, when the retransmit algorithm (using the transmitnumbers) declares a packet lost, the sender considers the packet to beonly conditionally lost, as it is possible that the SACK packetidentifying the reception of this packet was lost rather than the datapacket itself. The sender thus adds this packet to a list of potentiallylost packets, called the presumed lost list. Each time a SACK packetarrives, the known missing ranges of data from the SACK packet arecompared to the packets in the presumed lost list. Packets that containdata known to be missing are declared actually lost and are subsequentlyretransmitted. In this way, the two schemes are combined to give thesender better information about which packets have been lost and need tobe retransmitted.

Transaction Boundary Detection

In some embodiments, the appliance 200 or flow controller 220 applies atechnique referred to as transaction boundary detection. In oneembodiment, the technique pertains to ping-pong behaved connections. Atthe TCP layer, ping-pong behavior is when one communicant—a sender—sendsdata and then waits for a response from the other communicant—thereceiver. Examples of ping-pong behavior include remote procedure call,HTTP and others. The algorithms described above use retransmissiontimeout (RTO) to recover from the dropping of the last packet or packetsassociated with the transaction. Since the TCP RTO mechanism isextremely coarse in some embodiments, for example requiring a minimumone second value in all cases, poor application behavior may be seen inthese situations.

In one embodiment, the sender of data or a flow control module 220coupled to the sender detects a transaction boundary in the data beingsent. Upon detecting a transaction boundary, the sender or a flowcontrol module 220 sends additional packets, whose reception generatesadditional ACK or SACK responses from the receiver. Insertion of theadditional packets is preferably limited to balance between improvedapplication response time and network capacity utilization. The numberof additional packets that is inserted may be selected according to thecurrent loss rate associated with that connection, with more packetsselected for connections having a higher loss rate.

One method of detecting a transaction boundary is time based. If thesender has been sending data and ceases, then after a period of time thesender or flow control module 200 declares a transaction boundary. Thismay be combined with other techniques. For example, the setting of thePSH (TCP Push) bit by the sender in the TCP header may indicate atransaction boundary. Accordingly, combining the time-based approachwith these additional heuristics can provide for more accurate detectionof a transaction boundary. In another technique, if the sender or flowcontrol module 220 understands the application protocol, it can parsethe protocol data stream and directly determine transaction boundaries.In some embodiment, this last behavior can be used independent of anytime-based mechanism.

Responsive to detecting a transaction boundary, the sender or flowcontrol module 220 transmits additional data packets to the receiver tocause acknowledgements therefrom. The additional data packets shouldtherefore be such that the receiver will at least generate an ACK orSACK in response to receiving the data packet. In one embodiment, thelast packet or packets of the transaction are simply retransmitted. Thishas the added benefit of retransmitting needed data if the last packetor packets had been dropped, as compared to merely sending dummy datapackets. In another embodiment, fractions of the last packet or packetsare sent, allowing the sender to disambiguate the arrival of thesepackets from their original packets. This allows the receiver to avoidfalsely confusing any reordering adaptation algorithms. In anotherembodiment, any of a number of well-known forward error correctiontechniques can be used to generate additional data for the insertedpackets, allowing for the reconstruction of dropped or otherwise missingdata at the receiver.

In some embodiments, the boundary detection technique described hereinhelps to avoid a timeout when the acknowledgements for the last datapackets in a transaction are dropped. When the sender or flow controlmodule 220 receives the acknowledgements for these additional datapackets, the sender can determine from these additional acknowledgementswhether the last data packets have been received or need to beretransmitted, thus avoiding a timeout. In one embodiment, if the lastpackets have been received but their acknowledgements were dropped, aflow control module 220 generates an acknowledgement for the datapackets and sends the acknowledgement to the sender, thus communicatingto the sender that the data packets have been delivered. In anotherembodiment, if the last packets have not been received, a flow controlmodule 200 sends a packet to the sender to cause the sender toretransmit the dropped data packets.

Repacketization

In yet another embodiment, the appliance 200 or flow controller 220applies a repacketization technique for improving the flow of transportlayer network traffic. In some embodiments, performance of TCP isproportional to packet size. Thus increasing packet sizes improvesperformance unless it causes substantially increased packet loss ratesor other nonlinear effects, like IP fragmentation. In general, wiredmedia (such as copper or fibre optics) have extremely low bit-errorrates, low enough that these can be ignored. For these media, it isadvantageous for the packet size to be the maximum possible beforefragmentation occurs (the maximum packet size is limited by theprotocols of the underlying transmission media). Whereas fortransmission media with higher loss rates (e.g., wireless technologiessuch as WiFi, etc., or high-loss environments such as power-linenetworking, etc.), increasing the packet size may lead to lowertransmission rates, as media-induced errors cause an entire packet to bedropped (i.e., media-induced errors beyond the capability of thestandard error correcting code for that media), increasing the packetloss rate. A sufficiently large increase in the packet loss rate willactually negate any performance benefit of increasing packet size. Insome cases, it may be difficult for a TCP endpoint to choose an optimalpacket size. For example, the optimal packet size may vary across thetransmission path, depending on the nature of each link.

By inserting an appliance 200 or flow control module 220 into thetransmission path, the flow controller 220 monitors characteristics ofthe link and repacketizes according to determined link characteristics.In one embodiment, an appliance 200 or flow controller 220 repacketizespackets with sequential data into a smaller number of larger packets. Inanother embodiment, an appliance 200 or flow controller 220 repacketizespackets by breaking part a sequence of large packets into a largernumber of smaller packets. In other embodiments, an appliance 200 orflow controller 220 monitors the link characteristics and adjusts thepacket sizes through recombination to improve throughput.

QoS

Still referring to FIG. 2A, the flow controller 220, in someembodiments, may include a QoS Engine 236, also referred to as a QoScontroller. In another embodiment, the appliance 200 and/or networkoptimization engine 250 includes the QoS engine 236, for example,separately but in communication with the flow controller 220. The QoSEngine 236 includes any logic, business rules, function or operationsfor performing one or more Quality of Service (QoS) techniques improvingthe performance, operation or quality of service of any of the networkconnections. In some embodiments, the QoS engine 236 includes networktraffic control and management mechanisms that provide differentpriorities to different users, applications, data flows or connections.In other embodiments, the QoS engine 236 controls, maintains, or assuresa certain level of performance to a user, application, data flow orconnection. In one embodiment, the QoS engine 236 controls, maintains orassures a certain portion of bandwidth or network capacity for a user,application, data flow or connection. In some embodiments, the QoSengine 236 monitors the achieved level of performance or the quality ofservice corresponding to a user, application, data flow or connection,for example, the data rate and delay. In response to monitoring, the QoSengine 236 dynamically controls or adjusts scheduling priorities ofnetwork packets to achieve the desired level of performance or qualityof service.

In some embodiments, the QoS engine 236 prioritizes, schedules andtransmits network packets according to one or more classes or levels ofservices. In some embodiments, the class or level service mayinclude: 1) best efforts, 2) controlled load, 3) guaranteed or 4)qualitative. For a best efforts class of service, the appliance 200makes reasonable effort to deliver packets (a standard service level).For a controlled load class of service, the appliance 200 or QoS engine236 approximates the standard packet error loss of the transmissionmedium or approximates the behavior of best-effort service in lightlyloaded network conditions. For a guaranteed class of service, theappliance 200 or QoS engine 236 guarantees the ability to transmit dataat a determined rate for the duration of the connection. For aqualitative class of service, the appliance 200 or QoS engine 236 thequalitative service class is used for applications, users, data flows orconnection that require or desire prioritized traffic but cannotquantify resource needs or level of service. In these cases, theappliance 200 or QoS engine 236 determines the class of service orprioritization based on any logic or configuration of the QoS engine 236or based on business rules or policies. For example, in one embodiment,the QoS engine 236 prioritizes, schedules and transmits network packetsaccording to one or more policies as specified by the policy engine 295,295′.

Protocol Acceleration

The protocol accelerator 234 includes any logic, business rules,function or operations for optimizing, accelerating, or otherwiseimproving the performance, operation or quality of service of one ormore protocols. In one embodiment, the protocol accelerator 234accelerates any application layer protocol or protocols at layers 5-7 ofthe network stack. In other embodiments, the protocol accelerator 234accelerates a transport layer or a layer 4 protocol. In one embodiment,the protocol accelerator 234 accelerates layer 2 or layer 3 protocols.In some embodiments, the protocol accelerator 234 is configured,constructed or designed to optimize or accelerate each of one or moreprotocols according to the type of data, characteristics and/or behaviorof the protocol. In another embodiment, the protocol accelerator 234 isconfigured, constructed or designed to improve a user experience,response times, network or computer load, and/or network or bandwidthutilization with respect to a protocol.

In one embodiment, the protocol accelerator 234 is configured,constructed or designed to minimize the effect of WAN latency on filesystem access. In some embodiments, the protocol accelerator 234optimizes or accelerates the use of the CIFS (Common Internet FileSystem) protocol to improve file system access times or access times todata and files. In some embodiments, the protocol accelerator 234optimizes or accelerates the use of the NFS (Network File System)protocol. In another embodiment, the protocol accelerator 234 optimizesor accelerates the use of the File Transfer protocol (FTP).

In one embodiment, the protocol accelerator 234 is configured,constructed or designed to optimize or accelerate a protocol carrying asa payload or using any type and form of markup language. In otherembodiments, the protocol accelerator 234 is configured, constructed ordesigned to optimize or accelerate a HyperText Transfer Protocol (HTTP).In another embodiment, the protocol accelerator 234 is configured,constructed or designed to optimize or accelerate a protocol carrying asa payload or otherwise using XML (eXtensible Markup Language).

Transparency and Multiple Deployment Configuration

In some embodiments, the appliance 200 and/or network optimizationengine 250 is transparent to any data flowing across a networkconnection or link, such as a WAN link. In one embodiment, the appliance200 and/or network optimization engine 250 operates in such a mannerthat the data flow across the WAN is recognizable by any networkmonitoring, QOS management or network analysis tools. In someembodiments, the appliance 200 and/or network optimization engine 250does not create any tunnels or streams for transmitting data that mayhide, obscure or otherwise make the network traffic not transparent. Inother embodiments, the appliance 200 operates transparently in that theappliance does not change any of the source and/or destination addressinformation or port information of a network packet, such as internetprotocol addresses or port numbers. In other embodiments, the appliance200 and/or network optimization engine 250 is considered to operate orbehave transparently to the network, an application, client, server orother appliances or computing device in the network infrastructure. Thatis, in some embodiments, the appliance is transparent in that networkrelated configuration of any device or appliance on the network does notneed to be modified to support the appliance 200.

The appliance 200 may be deployed in any of the following deploymentconfigurations: 1) in-line of traffic, 2) in proxy mode, or 3) in avirtual in-line mode. In some embodiments, the appliance 200 may bedeployed inline to one or more of the following: a router, a client, aserver or another network device or appliance. In other embodiments, theappliance 200 may be deployed in parallel to one or more of thefollowing:: a router, a client, a server or another network device orappliance. In parallel deployments, a client, server, router or othernetwork appliance may be configured to forward, transfer or transitnetworks to or via the appliance 200.

In the embodiment of in-line, the appliance 200 is deployed inline witha WAN link of a router. In this way, all traffic from the WAN passesthrough the appliance before arriving at a destination of a LAN.

In the embodiment of a proxy mode, the appliance 200 is deployed as aproxy device between a client and a server. In some embodiments, theappliance 200 allows clients to make indirect connections to a resourceon a network. For example, a client connects to a resource via theappliance 200, and the appliance provides the resource either byconnecting to the resource, a different resource, or by serving theresource from a cache. In some cases, the appliance may alter theclient's request or the server's response for various purposes, such asfor any of the optimization techniques discussed herein. In otherembodiments, the appliance 200 behaves as a transparent proxy, byintercepting and forwarding requests and responses transparently to aclient and/or server. Without client-side configuration, the appliance200 may redirect client requests to different servers or networks. Insome embodiments, the appliance 200 may perform any type and form ofnetwork address translation, referred to as NAT, on any network traffictraversing the appliance.

In some embodiments, the appliance 200 is deployed in a virtual in-linemode configuration. In this embodiment, a router or a network devicewith routing or switching functionality is configured to forward,reroute or otherwise provide network packets destined to a network tothe appliance 200. The appliance 200 then performs any desiredprocessing on the network packets, such as any of the WAN optimizationtechniques discussed herein. Upon completion of processing, theappliance 200 forwards the processed network packet to the router totransmit to the destination on the network. In this way, the appliance200 can be coupled to the router in parallel but still operate as it ifthe appliance 200 were inline. This deployment mode also providestransparency in that the source and destination addresses and portinformation are preserved as the packet is processed and transmitted viathe appliance through the network.

End Node Deployment

Although the network optimization engine 250 is generally describedabove in conjunction with an appliance 200, the network optimizationengine 250, or any portion thereof, may be deployed, distributed orotherwise operated on any end node, such as a client 102 and/or server106. As such, a client or server may provide any of the systems andmethods of the network optimization engine 250 described herein inconjunction with one or more appliances 200 or without an appliance 200.

Referring now to FIG. 2B, an example embodiment of the networkoptimization engine 250 deployed on one or more end nodes is depicted.In brief overview, the client 102 may include a first networkoptimization engine 250′ and the server 106 may include a second networkoptimization engine 250″. The client 102 and server 106 may establish atransport layer connection and exchange communications with or withouttraversing an appliance 200.

In one embodiment, the network optimization engine 250′ of the client102 performs the techniques described herein to optimize, accelerate orotherwise improve the performance, operation or quality of service ofnetwork traffic communicated with the server 106. In another embodiment,the network optimization engine 250″ of the server 106 performs thetechniques described herein to optimize, accelerate or otherwise improvethe performance, operation or quality of service of network trafficcommunicated with the client 102. In some embodiments, the networkoptimization engine 250′ of the client 102 and the network optimizationengine 250″ of the server 106 perform the techniques described herein tooptimize, accelerate or otherwise improve the performance, operation orquality of service of network traffic communicated between the client102 and the server 106. In yet another embodiment, the networkoptimization engine 250′ of the client 102 performs the techniquesdescribed herein in conjunction with an appliance 200 to optimize,accelerate or otherwise improve the performance, operation or quality ofservice of network traffic communicated with the client 102. In stillanother embodiment, the network optimization engine 250″ of the server106 performs the techniques described herein in conjunction with anappliance 200 to optimize, accelerate or otherwise improve theperformance, operation or quality of service of network trafficcommunicated with the server 106.

C. Client Agent

Referring now to FIG. 3, an embodiment of a client agent 120 isdepicted. The client 102 has a client agent 120 for establishing,exchanging, managing or controlling communications with the appliance200, appliance 205 and/or server 106 via a network 104. In someembodiments, the client agent 120, which may also be referred to as aWAN client, accelerates WAN network communications and/or is used tocommunicate via appliance 200 on a network. In brief overview, theclient 102 operates on computing device 100 having an operating systemwith a kernel mode 302 and a user mode 303, and a network stack 267 withone or more layers 310 a-310 b. The client 102 may have installed and/orexecute one or more applications. In some embodiments, one or moreapplications may communicate via the network stack 267 to a network 104.One of the applications, such as a web browser, may also include a firstprogram 322. For example, the first program 322 may be used in someembodiments to install and/or execute the client agent 120, or anyportion thereof. The client agent 120 includes an interceptionmechanism, or interceptor 350, for intercepting network communicationsfrom the network stack 267 from the one or more applications.

As with the appliance 200, the client has a network stack 267 includingany type and form of software, hardware, or any combinations thereof,for providing connectivity to and communications with a network 104. Thenetwork stack 267 of the client 102 includes any of the network stackembodiments described above in conjunction with the appliance 200. Insome embodiments, the client agent 120, or any portion thereof, isdesigned and constructed to operate with or work in conjunction with thenetwork stack 267 installed or otherwise provided by the operatingsystem of the client 102.

In further details, the network stack 267 of the client 102 or appliance200 (or 205) may include any type and form of interfaces for receiving,obtaining, providing or otherwise accessing any information and datarelated to network communications of the client 102. In one embodiment,an interface to the network stack 267 includes an applicationprogramming interface (API). The interface may also have any functioncall, hooking or filtering mechanism, event or call back mechanism, orany type of interfacing technique. The network stack 267 via theinterface may receive or provide any type and form of data structure,such as an object, related to functionality or operation of the networkstack 267. For example, the data structure may include information anddata related to a network packet or one or more network packets. In someembodiments, the data structure includes, references or identifies aportion of the network packet processed at a protocol layer of thenetwork stack 267, such as a network packet of the transport layer. Insome embodiments, the data structure 325 is a kernel-level datastructure, while in other embodiments, the data structure 325 is auser-mode data structure. A kernel-level data structure may have a datastructure obtained or related to a portion of the network stack 267operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 267 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 267. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 267 to an application while a second portion 310 a of the networkstack 267 provides access to a network. In some embodiments, a firstportion 310 a of the network stack has one or more upper layers of thenetwork stack 267, such as any of layers 5-7. In other embodiments, asecond portion 310 b of the network stack 267 includes one or more lowerlayers, such as any of layers 1-4. Each of the first portion 310 a andsecond portion 310 b of the network stack 267 may include any portion ofthe network stack 267, at any one or more network layers, in user-mode303, kernel-mode, 302, or combinations thereof, or at any portion of anetwork layer or interface point to a network layer or any portion of orinterface point to the user-mode 302 and kernel-mode 203.

The interceptor 350 may include software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercepts or otherwise receives a network communication at any point inthe network stack 267, and redirects or transmits the networkcommunication to a destination desired, managed or controlled by theinterceptor 350 or client agent 120. For example, the interceptor 350may intercept a network communication of a network stack 267 of a firstnetwork and transmit the network communication to the appliance 200 fortransmission on a second network 104. In some embodiments, theinterceptor 350 includes or is a driver, such as a network driverconstructed and designed to interface and work with the network stack267. In some embodiments, the client agent 120 and/or interceptor 350operates at one or more layers of the network stack 267, such as at thetransport layer. In one embodiment, the interceptor 350 includes afilter driver, hooking mechanism, or any form and type of suitablenetwork driver interface that interfaces to the transport layer of thenetwork stack, such as via the transport driver interface (TDI). In someembodiments, the interceptor 350 interfaces to a first protocol layer,such as the transport layer and another protocol layer, such as anylayer above the transport protocol layer, for example, an applicationprotocol layer. In one embodiment, the interceptor 350 includes a drivercomplying with the Network Driver Interface Specification (NDIS), or aNDIS driver. In another embodiment, the interceptor 350 may be amin-filter or a mini-port driver. In one embodiment, the interceptor350, or portion thereof, operates in kernel-mode 202. In anotherembodiment, the interceptor 350, or portion thereof, operates inuser-mode 203. In some embodiments, a portion of the interceptor 350operates in kernel-mode 202 while another portion of the interceptor 350operates in user-mode 203. In other embodiments, the client agent 120operates in user-mode 203 but interfaces via the interceptor 350 to akernel-mode driver, process, service, task or portion of the operatingsystem, such as to obtain a kernel-level data structure 225. In furtherembodiments, the interceptor 350 is a user-mode application or program,such as application.

In one embodiment, the interceptor 350 intercepts or receives anytransport layer connection requests. In these embodiments, theinterceptor 350 executes transport layer application programminginterface (API) calls to set the destination information, such asdestination IP address and/or port to a desired location for thelocation. In this manner, the interceptor 350 intercepts and redirectsthe transport layer connection to an IP address and port controlled ormanaged by the interceptor 350 or client agent 120. In one embodiment,the interceptor 350 sets the destination information for the connectionto a local IP address and port of the client 102 on which the clientagent 120 is listening. For example, the client agent 120 may comprise aproxy service listening on a local IP address and port for redirectedtransport layer communications. In some embodiments, the client agent120 then communicates the redirected transport layer communication tothe appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may include two agents120 and 120′. In one embodiment, a first agent 120 may include aninterceptor 350 operating at the network layer of the network stack 267.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 210 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 267. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 267 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 267 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor 350 may operate ator interface with the network stack 267 in a manner transparent to anyapplication, a user of the client 102, the client 102 and/or any othercomputing device 100, such as a server or appliance 200, 206, incommunications with the client 102. The client agent 120, or any portionthereof, may be installed and/or executed on the client 102 in a mannerwithout modification of an application. In one embodiment, the clientagent 120, or any portion thereof, is installed and/or executed in amanner transparent to any network configuration of the client 102,appliance 200, 205 or server 106. In some embodiments, the client agent120, or any portion thereof, is installed and/or executed withmodification to any network configuration of the client 102, appliance200, 205 or server 106. In one embodiment, the user of the client 102 ora computing device in communications with the client 102 are not awareof the existence, execution or operation of the client agent 12, or anyportion thereof. As such, in some embodiments, the client agent 120and/or interceptor 350 is installed, executed, and/or operatedtransparently to an application, user of the client 102, the client 102,another computing device, such as a server or appliance 200, 2005, orany of the protocol layers above and/or below the protocol layerinterfaced to by the interceptor 350.

The client agent 120 includes a streaming client 306, a collection agent304, SSL VPN agent 308, a network optimization engine 250, and/oracceleration program 302. In one embodiment, the client agent 120 is anIndependent Computing Architecture (ICA) client, or any portion thereof,developed by Citrix Systems, Inc. of Fort Lauderdale, Fla., and is alsoreferred to as an ICA client. In some embodiments, the client agent 120has an application streaming client 306 for streaming an applicationfrom a server 106 to a client 102. In another embodiment, the clientagent 120 includes a collection agent 304 for performing end-pointdetection/scanning and collecting end-point information for theappliance 200 and/or server 106. In some embodiments, the client agent120 has one or more network accelerating or optimizing programs oragents, such as an network optimization engine 250 and an accelerationprogram 302. In one embodiment, the acceleration program 302 acceleratescommunications between client 102 and server 106 via appliance 205′. Insome embodiments, the network optimization engine 250 provides WANoptimization techniques as discussed herein.

The streaming client 306 is an application, program, process, service,task or set of executable instructions for receiving and executing astreamed application from a server 106. A server 106 may stream one ormore application data files to the streaming client 306 for playing,executing or otherwise causing to be executed the application on theclient 102. In some embodiments, the server 106 transmits a set ofcompressed or packaged application data files to the streaming client306. In some embodiments, the plurality of application files arecompressed and stored on a file server within an archive file such as aCAB, ZIP, SIT, TAR, JAR or other archive. In one embodiment, the server106 decompresses, unpackages or unarchives the application files andtransmits the files to the client 102. In another embodiment, the client102 decompresses, unpackages or unarchives the application files. Thestreaming client 306 dynamically installs the application, or portionthereof, and executes the application. In one embodiment, the streamingclient 306 may be an executable program. In some embodiments, thestreaming client 306 may be able to launch another executable program.

The collection agent 304 is an application, program, process, service,task or set of executable instructions for identifying, obtaining and/orcollecting information about the client 102. In some embodiments, theappliance 200 transmits the collection agent 304 to the client 102 orclient agent 120. The collection agent 304 may be configured accordingto one or more policies of the policy engine 236 of the appliance. Inother embodiments, the collection agent 304 transmits collectedinformation on the client 102 to the appliance 200. In one embodiment,the policy engine 236 of the appliance 200 uses the collectedinformation to determine and provide access, authentication andauthorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 is an end-point detectionand scanning program, which identifies and determines one or moreattributes or characteristics of the client. For example, the collectionagent 304 may identify and determine any one or more of the followingclient-side attributes: 1) the operating system an/or a version of anoperating system, 2) a service pack of the operating system, 3) arunning service, 4) a running process, and 5) a file. The collectionagent 304 may also identify and determine the presence or version of anyone or more of the following on the client: 1) antivirus software, 2)personal firewall software, 3) anti-spam software, and 4) internetsecurity software. The policy engine 236 may have one or more policiesbased on any one or more of the attributes or characteristics of theclient or client-side attributes.

The SSL VPN agent 308 is an application, program, process, service, taskor set of executable instructions for establishing a Secure Socket Layer(SSL) virtual private network (VPN) connection from a first network 104to a second network 104′, 104″, or a SSL VPN connection from a client102 to a server 106. In one embodiment, the SSL VPN agent 308establishes a SSL VPN connection from a public network 104 to a privatenetwork 104′ or 104″. In some embodiments, the SSL VPN agent 308 worksin conjunction with appliance 205 to provide the SSL VPN connection. Inone embodiment, the SSL VPN agent 308 establishes a first transportlayer connection with appliance 205. In some embodiment, the appliance205 establishes a second transport layer connection with a server 106.In another embodiment, the SSL VPN agent 308 establishes a firsttransport layer connection with an application on the client, and asecond transport layer connection with the appliance 205. In otherembodiments, the SSL VPN agent 308 works in conjunction with WANoptimization appliance 200 to provide SSL VPN connectivity.

In some embodiments, the acceleration program 302 is a client-sideacceleration program for performing one or more acceleration techniquesto accelerate, enhance or otherwise improve a client's communicationswith and/or access to a server 106, such as accessing an applicationprovided by a server 106. The logic, functions, and/or operations of theexecutable instructions of the acceleration program 302 may perform oneor more of the following acceleration techniques: 1) multi-protocolcompression, 2) transport control protocol pooling, 3) transport controlprotocol multiplexing, 4) transport control protocol buffering, and 5)caching via a cache manager. Additionally, the acceleration program 302may perform encryption and/or decryption of any communications receivedand/or transmitted by the client 102. In some embodiments, theacceleration program 302 performs one or more of the accelerationtechniques in an integrated manner or fashion. Additionally, theacceleration program 302 can perform compression on any of theprotocols, or multiple-protocols, carried as a payload of a networkpacket of the transport layer protocol.

In one embodiment, the acceleration program 302 is designed, constructedor configured to work with appliance 205 to provide LAN sideacceleration or to provide acceleration techniques provided viaappliance 205. For example, in one embodiment of a NetScaler appliance205 manufactured by Citrix Systems, Inc., the acceleration program 302includes a NetScaler client. In some embodiments, the accelerationprogram 302 provides NetScaler acceleration techniques stand-alone in aremote device, such as in a branch office. In other embodiments, theacceleration program 302 works in conjunction with one or more NetScalerappliances 205. In one embodiment, the acceleration program 302 providesLAN-side or LAN based acceleration or optimization of network traffic.

In some embodiments, the network optimization engine 250 may bedesigned, constructed or configured to work with WAN optimizationappliance 200. In other embodiments, network optimization engine 250 maybe designed, constructed or configured to provide the WAN optimizationtechniques of appliance 200, with or without an appliance 200. Forexample, in one embodiment of a WANScaler appliance 200 manufactured byCitrix Systems, Inc. the network optimization engine 250 includes theWANscaler client. In some embodiments, the network optimization engine250 provides WANScaler acceleration techniques stand-alone in a remotelocation, such as a branch office. In other embodiments, the networkoptimization engine 250 works in conjunction with one or more WANScalerappliances 200.

In another embodiment, the network optimization engine 250 includes theacceleration program 302, or the function, operations and logic of theacceleration program 302. In some embodiments, the acceleration program302 includes the network optimization engine 250 or the function,operations and logic of the network optimization engine 250. In yetanother embodiment, the network optimization engine 250 is provided orinstalled as a separate program or set of executable instructions fromthe acceleration program 302. In other embodiments, the networkoptimization engine 250 and acceleration program 302 are included in thesame program or same set of executable instructions.

In some embodiments and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or anyportion thereof, automatically, silently, transparently, or otherwise.In one embodiment, the first program 322 is a plugin component, such anActiveX control or Java control or script that is loaded into andexecuted by an application. For example, the first program comprises anActiveX control loaded and run by a web browser application, such as inthe memory space or context of the application. In another embodiment,the first program 322 comprises a set of executable instructions loadedinto and run by the application, such as a browser. In one embodiment,the first program 322 is designed and constructed program to install theclient agent 120. In some embodiments, the first program 322 obtains,downloads, or receives the client agent 120 via the network from anothercomputing device. In another embodiment, the first program 322 is aninstaller program or a plug and play manager for installing programs,such as network drivers and the client agent 120, or any portionthereof, on the operating system of the client 102.

In some embodiments, each or any of the portions of the client agent120—a streaming client 306, a collection agent 304, SSL VPN agent 308, anetwork optimization engine 250, acceleration program 302, andinterceptor 350—may be installed, executed, configured or operated as aseparate application, program, process, service, task or set ofexecutable instructions. In other embodiments, each or any of theportions of the client agent 120 may be installed, executed, configuredor operated together as a single client agent 120.

D. Systems and Methods for Data Flow Control

Referring now to FIG. 4, some embodiments of a system for efficient dataflow control are illustrated. The illustration shows a flow of data in asystem comprising a sender and an appliance disposed in the path of thedata stream transmitted between the sender and the receiver. FIG. 4 alsoillustrates embodiments of a system having an appliance 200 disposedalong a data path between a server and a receiver, as well asembodiments wherein two or more appliances are deployed along the samedata path.

In a brief overview, FIG. 4 illustrates a sender sending data to areceiver. Since data may be upstream and downstream, both, the sender orthe receiver may either be a client 102 or a server 106. In someembodiments, the sender or the receiver may be an appliance 200. Asshown in FIG. 4, the sender may include an application 405 comprising adata generator 415. Either the application 405 or the data generator 415may generate data, such as interactive data 410 or bulk data 411.Herein, interactive data 410 and bulk data 411 may also be referred toas data portions 410 and 411. FIG. 4 illustrates the interactive data410 and the bulk data 411 flowing into a network optimizer 420. Thenetwork optimizer 420 may include a data transfer manager 430 and a datatransfer model 440. The network optimizer 420, in a plurality ofembodiments, processes the data and may manage, control or improve theprocess of sending data. FIG. 4 also depicts the data portions 410 and411 formed into data packets 480A-N and sent over the network from the466A port of the sender to the 266A port of the appliance 200. Theappliance 200, in addition to the aforementioned packet processingengine 240, the flow controller 220 and the compression engine 238 mayalso comprise an intermediary model 455 and a bandwidth measurer 450. Insome embodiments, the appliance 200 processes data packets 480 andformats the packets into compressed data packets 495 which are sent overthe network to the receiver.

In the embodiments depicted by FIG. 4, the sender is shown as anappliance comprising a number of components. It should be understood thesender may be any type of device sending or receiving communication viaa network. In some embodiments, the sender is any system, apparatus or aunit communicating with another device. In a number of embodiments, thesender is a device running an application generating bulk data 411 ordata which is not real time data. In a plurality of embodiments, thesender is a device running an application generating an interactive data410 or a real time data. In some embodiments, the sender comprises adata generator. In some embodiments, the sender comprises a device, aunit, a program or a system controlling the flow of information or datatransmitted by the sender. In a plurality of embodiments, the sendercomprises a compression engine or a data formatting unit. In someembodiments, the sender is a device or a system capable of transmittingor receiving information or data.

Application 405 may be any application, computer program, firmware orsoftware running on a sender. In a plurality of embodiments, theapplication 405 is a device, system, unit or a software generating orsending data. Application 405 may comprise a data generator 415generating interactive data 410 or bulk data 411. In a number ofembodiments, application 405 generates interactive data 410 or bulk data411. In specific embodiments, application 405 or data generator 415generate a combination of bulk data 411 and interactive data 410. Thedata may be generated in a continuous stream and may be of any format.Sometimes, the data is generated in discrete steps or in non-continuousway. In some embodiments, data generated by application 405 includes anaction, instruction or data from the user. Such actions, instructions ordata may comprise a movement of a mouse on a user's computer, a click ofa mouse on a computer, an input from a keyboard, a video or audiostream, a computer program or an application, a video game or any kindof software or computer generated data. In some embodiments, application405 generates a data such as a display of an action or a command of theuser such as a letter typed by the user in an application such as a texteditor. The application 405 may comprise any type or form ofvirtualization application, program, software or computer service. Insome embodiments, the application 405 comprises a remote displayapplication, a remote access application or a web browser. In a numberof embodiments, application 405 is a computer operating system. In oneembodiment, the application is, comprises or interfaces with an ICAclient, developed by Citrix Systems, Inc. of Fort Lauderdale, Fla. Inother embodiments, the application is, comprises or interfaces with aRemote Desktop (RDP) client, developed by Microsoft Corporation ofRedmond, Wash. In a plurality of embodiments, application 405 is anytype of an editing application, calculating application, storageapplication, planning application, graphical or a video application,audio application, an instant messenger application or any other type ofapplication which may be run on a client 102, a server 106 or otherwiseto produce or generate data.

In some embodiments, the application uses a protocol having multiplechannels for communicating bulk and interactive data. A communicationchannel may be any medium, path or means of communication used for aparticular type of transmission or data. In some embodiments,communication channels may be used for transmitting multiple kinds ofdata. Sometimes, channels are defined by a communication protocol usedfor communication. In one embodiment, one or more channels are used forcommunicating interactive data. In some embodiments, one or morechannels are used for communicating bulk data. In some embodiments, oneor more channels are used for interactive data while one or more otherchannels are used for bulk data. In yet another embodiments, a singlecommunication channel may be used for communicating bulk data andinteractive data. In one embodiment, the channels of communication areestablished and maintained by a protocol of an ICA client or a RemoteDesktop Client protocol.

Data generator 415 may be any application, software, hardware, device ora unit generating or producing data. Though, as illustrated by FIG. 4,data generator 415 may be comprised or controlled by the application405, data generator 415 may also be a standalone, independent unitoperating and producing data. Data generator 415 may comprise any typeand form of software, application service, library, database, process,task or set of executable instructions. In a plurality of embodiments,data generator 415 is a component managing data generated by anotherapplication or a software. In some embodiments, data generator 415 is aunit or a system processing, preparing, formatting or shaping the datagenerated by an application for network optimizer. In a number ofembodiments, data generator 415 operates as an intermediate step or aninterface for the data outputted by the application 405. Data generator415 may prepare, format or process the data and interface with networkoptimizer 420. In some embodiments, data generator 415 is a softwarecomponent managing or transforming the data created by the application405.

Data generator 415 may generate any type of data, code, instruction orcommunication. In some embodiments, data generator 415 generatesinteractive data 410. In some embodiments, data generator 415 generatesbulk data 411. Data generator 415 may generate any combination ofinteractive and bulk data in any format. Data generator 415 may be acomponent of a software or an application producing data of any kind.Data generator 415 may be a unit producing an output, such as a video orgraphical output. Sometimes, data generator may produce an output for agraphical user interface.

Interactive data 410 may be any type of data resulting from interactionbetween one device and another device. Interactive data 410 may be anykind of real-time data. Interactive data 410 may also be any data thatupdates on its own schedule, such as stock quotes, manufacturingstatistics, web server loads, warehouse activity, traffic and more.Sometimes, interactive data 410 may be any type and form of dataresulting from user interaction with a client 102, server 106,intermediary appliance 200 or any other device on a network 104. In someembodiment, interactive data 410 is output from an application, such asdisplay output, for example, display output transmitted via remotedisplay protocol. In some embodiments, interactive data 410 is dataresulting from a computer mouse or an input on a computer. In aplurality of embodiments, interactive data 410 is a letter, character ora symbol typed in from the keyboard of a computer. In a number ofembodiments, interactive data 410 is a continuously updating data streamfrom an application 405 or a data generator 415. In a plurality ofembodiments, interactive data 410 is related to any data produced by theapplication, by the user or by the sender. In some embodiments,interactive data 410 is a constantly changing data while in otherembodiments 410 interactive data does not have to be constantlychanging. In a number of embodiments, interactive data 410 comprises acomponent of data which is not changing. In some embodiments,interactive data 410 comprises any type of data that may have a varyingtime of data generated. In a number of embodiments, interactive data 410is generated within a periodic and predefined generation time which maybe constant or may be changing. Interactive data 410 may be any datawhose transfer in a remote desktop application from a server to a clientis of a higher priority than other type of data whose transfer at alater time will not impact the quality of user experience.

In a plurality of embodiments, interactive data 410 is user inputdependent. In certain embodiments, interactive data 410 has a periodicgeneration time wherein a period of time in which an amount of data isgenerated varies in duration from another period of time in whichanother amount of data is generated. In a number of embodiments,interactive data 410 is generated in a continuous or a discrete fashionin which each discrete amount of time within which an amount of data isgenerated may have a different amount of data generated from anotheramount of data generated in another discrete amount of time. In someembodiments, interactive data 410 comprises a data stream. In aplurality of embodiments, interactive data 410 comprises a user data ora payload. In a plurality of embodiments, interactive data 410 comprisesa frame or a screen shot of an application as displayed on the screen ofa computer.

Bulk data 411 may be any type of data having less of a priority to betransferred than interactive data. Bulk data 411 may be any data notbeing subject to change over a longer period of time than the period oftime within which interactive data 410 is going to change. Bulk data 411may be data comprising information regarding files to be printed. Bulkdata 411 may be data comprising a large chunk or a large size of datawhose transfer is at a lower priority than the transfer of theinteractive data 410. In some embodiments, bulk data 411 comprises anamount of data greater than a predetermined threshold. In manyembodiments, bulk data 411 is any type of non real-time data. In someembodiments, bulk data 411 comprises commands, data or instructions forprinting a file or a program. In a number of embodiments, bulk data 411comprises any data including components of data that are unchanging orremaining constant over a relatively short or a relatively long periodof time. In some embodiments, bulk data 411 comprises portions of datathat are changing or do not remain constant over a relatively short or arelatively long period of time. In a plurality of embodiments, bulk data411 comprises a file, a video, an audio, an application, or data from adata base. In some embodiments, bulk data 411 comprises elements of agraphical user interface. In a plurality of embodiments, bulk data 411comprises a user data or a payload.

Network optimizer 420 may be any type of a device, structure or anapplication which improves, controls, manages or optimizes a flow ofdata. Network optimizer 420 may be a system or a unit controlling andmanaging the flow of data transferred between the sender and a receiver.A network optimizer 420 may be any component, unit or a system receivinginteractive data 410 and bulk data 411 and controlling the output flowof the interactive data 410 and the bulk data 411 from the sender to thereceiver. Network optimizer 420 may be any component, a function or aunit, comprising any hardware, software, circuitry or logic for forming,formatting, managing and controlling the flow of data transmitted by thesender. The network optimizer 420 may be any device, application or aunit distinguishing between bulk data 411 and interactive data 410.Network optimizer 420 may separate or sort the real time data from theinteractive data in order to manage or control the transfer of the data.In one embodiment, network optimizer 420 identifies bulk data from theinteractive data and formats or sorts the bulk data and interactive datain their respective packets based on their identification. In anotherembodiment, the network optimizer 420 processes data generated by theapplication 405 or the data generator 415 in order to control the amountof bulk data 411 and interactive data 410 to be transmitted over thenetwork. Network optimizer 420 may comprise a model used fortransmission of the interactive data 410 and bulk data 411 over thenetwork to the receiver. The model may comprise any type of statisticsused for anticipating or estimating a more or the most efficient amountof data to be transmitted over the network. In some embodiments, networkoptimizer 420 comprises a data transfer model which comprisesinformation relating the data congestion and data occupancy on thenetwork. The network optimizer may assist the data transfer manager inselecting an optimal or desired amount of data to be sent over thenetwork and/or timing of the data to be sent over the network. In anumber of embodiments, network optimizer reorganizes or reformats datain data packets 480. The network optimizer comprises the networkoptimization engine or any portion thereof.

Network optimizer 420 may comprise a model for managing or controllingtransmission of data to a receiver. The model of the network optimizer420 may be any model within the network optimizer 420, such as the datatransfer model 440. The model of the network optimizer 420 may also beinterchangeably referred to as the data transfer model 440 or thesender's model. Network optimizer 420 may utilize one or more models tocontrol various aspects of the data or information transmission control,such as amounts of information to be transmitted, type of information tobe transmitted or the timing of the amounts of information to betransmitted. Sometimes, one or more models of the network optimizer 420utilizes statistics such as bandwidth of the network, congestion of thenetwork or traffic affecting sender or the receiver, backlog of theinformation, and similar in order to determine the amount of data to besent to the receiver and the time at which to send the amount of data.The data or information transmitted to the receiver using the model maybe referred to as the bulk data 411 and/or interactive data 410.

In many embodiments, the model of the network optimizer 420 is updatedby messages from a model of the appliance 200, such as the intermediarymodel 455. The intermediary model 455 of the appliance 200 may includemore updated statistics, metrics or values for determinations ofbandwidth between the sender and the receiver, compression ratio of adata compressed, or a backlog value of an amount of data to betransmitted. The intermediary model 455 upon realizing that the moreupdated determination or estimate of the value of bandwidth is moreaccurate than the value of bandwidth of the model of the networkoptimizer 420 of the sender, may send to the sender or to the sender'smodel the more updated value of bandwidth, the more updated value ofcompression ratio of transmitted data, or the backlog value. In someembodiments, the intermediary model sends updates of bandwidth values ormeasurements as changes occur. In other embodiments, the intermediarymodel sends updates of bandwidth values at a predetermined frequency. Insome embodiments, the intermediary model sends updates of bandwidthvalues responsive to any type and form of event. In one embodiment, theintermediary model sends updates of bandwidth values responsive to arequest.

The network optimizer 420 may update the sender's model in response tothe received message comprising the updated values of the bandwidth fromthe intermediary model 455. Such updates may enable the networkoptimizer 420 to more accurately determine the amount of bulk data 411and interactive data 410 to be transmitted and the timing of the amountof each type of data to be transmitted. Network optimizer 420 mayutilize the data transfer manager 430 to control the amount and type ofdata or information to be transmitted utilizing the data transfer model440 to determine the amount and timing of the data to transmit to thereceiver via the appliance 200. Network optimizer 420 may utilizestatistics or values from the model of the network optimizer 420, orfrom data transfer model 440, to determine the amount and the timing oftransmission for each one of the interactive data 410 and bulk data 411.Network optimizer 420 may then utilize data transfer manager 430 toexecute the transmission using the amount and the timing determined bythe model, such as the data transfer model 440, or any other model ofthe network optimizer 420.

Data transfer manager 430 may be any type of device, software,application or a unit for controlling or managing the transfer ortransmission of data from the sender to the receiver. Data transfermanager 430 may be a communication device capable of controlling theamount of transmitted information and the timing of the amount of theinformation transmitted. Data transfer manager 420 may be any device,unit, software or a component of the sender transmitting informationusing the values and statistics provided by any network optimizer 420model, such as the data transfer model 440. Data transfer manager maycomprise any hardware, software, circuitry, processors, logic andprocessing circuits, memory, firmware, logical functions or componentsto enable control and management of the data transmitted. Data transfermanager 430 In some embodiments, a data transfer manager 430 comprisessoftware. The data transfer manager 430 may comprise any components orfunctionality to manage and maintain the backlog of the information tobe transmitted. Data transfer manager 430 may comprise any features orfunctionality of a network optimizer 420, flow controller 220 or a datatransfer model 440. In some embodiments, data transfer manager 430 iscombined or fused into a single device, unit, function, software or acomponent together with the network optimizer 420, flow controller 220and data transfer model 440. In some embodiments, data transfer manager430 is a part of the network optimizer 420. In some embodiments, datatransfer manager 430 is not comprised by the network optimizer 420, butcommunicates with it. In some embodiments, data transfer manager 430 isa part of the sender, while in other embodiments data transfer manager430 is a component separate from the sender.

The network optimizer 420 and data transfer manager 430 may eachcomprise the functionality to determine when to transmit data, messagesor information and determine the amount of data, messages or informationto transmit. The network optimizer 420 and transfer manager 430 maycontrol transmission of the information as determined as well as thetiming of the transmission. The data transfer manager 430 may prioritizethe order, timing and size of data to transmit. The data transfermanager 430 may distinguish between bulk and interactive data and managetransmission according to the amount of each. Sometimes, networkoptimizer 420 or the data transfer manager 430 utilize bandwidthestimation from the bandwidth monitor 720 to determine the amount ofdata to be transmitted. Sometimes, network optimizer 420 and datatransfer manager 430 utilize compression statistics from the compressionengine 238 or the backlog value from the appliance 200, or theintermediary, to determine the amount of data to transmit and the timingto transmit the data. The backlog of the intermediary 200 may be made upof the data previously transmitted by the sender but not yet forwardedto the receiver for whatever reason.

Data transfer manager 430 may utilize any statistics or metrics from anysource to execute transmission of the data. In some embodiments, datatransfer manager 430 may use statistics or metrics, such as thebandwidth information from a bandwidth monitoring component, internal orexternal to the sender, in order to manage the transmission of the data.In some embodiments, a data transfer manager 430 determines a nextamount of the data to be sent based on the value of bandwidth known tothe data transfer manager 430. In certain embodiments, a data transfermanager 430 determines a timing of the next amount of data to be sentbased on the value of bandwidth known to the data transfer manager 430.In a plurality of embodiments, a data transfer manager 430 determines anext amount of the data to be sent or the timing of the next amount ofdata to be sent based on the compression ratio of a data compressed usedby appliance 200. In certain embodiments, a data transfer manager 430determines a next amount of the data to be sent or the timing of thenext amount of data to be sent based on backlog information of the datato be transferred backlogged in a queue or stored in a memory beforetransmitted to the receiver. Backlog information may include any type ofinformation, bulk or interactive data 411 and 410, metrics or statisticson any data queued to be transmitted or the updated values or messagesto be transmitted between the sender's models, such as the data transfermodel 440 and the receiver's models, such as the intermediary model 455of the appliance 200 or a model of the receiver receiving the data fromthe appliance 200.

Data transfer manager 430 may determine any of: the timing or the amountof interactive data 410 to be transmitted, the timing or the amount ofbulk data 411 to be transmitted, the amount of data as well as thespecific portion of data to be sent during the next scheduled datatransmitting event or the specific data from the determined amount to besent during the next scheduled data transmitting event. In certainembodiments, the data transfer manager 430 makes determinations based ona compression ratio value of a compression ratio of a data compressed byan intermediary or an appliance 200, a backlog value of an amount ofdata to be sent from the appliance 200 to the receiver, or a bandwidthvalue expressing the available bandwidth of the network 104.

Data transfer model 440 may be any component or a unit used to store,represent or maintain a model to determine the amount of data to betransmitted and the timing of the data to be transmitted. Data transfermodel 440 may be also referred to as the model of the network optimizer420 described above. Network transfer model 420 may comprise a number ofmodels and each of the models may comprise each and every functionalityof the data transfer model 440 and any model of network optimizer 420described above. Data transfer model 440 may comprise a software, analgorithm, an application, a logic unit, a memory, a processor, ahardware or any other component enabling the data transfer model 440 tomaintain or update the values, metrics or statistics used to determinethe amount and timing of the transmissions by the sender. The values,metrics or statistics may be values such as the bandwidth of thenetwork, the compression ratio of a data compressed by either the senderor the appliance 200, the backlog value of an amount data backlogged fortransmission either by the sender or by the appliance 200, the bandwidthbetween the sender and the appliance 200, the bandwidth between theappliance 200 and the receiver, the bandwidth between the sender and thereceiver via the appliance 200, and more.

Data transfer model 440 may also receive from either the appliance 200or the receiver the message which may comprise updated values of any ofthe bandwidth, compression ratios or backlog values. Data transfer model440 may update the values, metrics or the statistics with the newreceived values from the received message. Data transfer model 440 maytransmit messages back and forth with the model of the appliance or thereceiver, such as the intermediary model 455 for example, in order toexchange the latest values, metrics and statistics and update thesender's model, such as the data transfer model 440. The model of theappliance 200, the intermediary model 455, being more likely to havemore updated and more correct values, may provide the data transfermodel 440 the latest values and statistics enabling the networkoptimizer 420 or the data transfer manager 430 to more accuratelycontrol the transmission of the data or information from the sender.Messages comprising the updated values used by the models may betransmitted between the sender and the receiver or between the senderand the intermediary, also referred to as the appliance 200, via datapackets 480 and compressed data packets 495. In some embodiments, themessages may be transmitted together with interactive data 410 and bulkdata 411. Sometimes, the messages may be transmitted individually andseparately from the data or other information transmitted between thesender and the receiver.

Data transfer model 440 may monitor, estimate and/or predict any of thestatistics affecting the transmission of the information or data betweenthe sender and the receiver. In some embodiments, data transfer model440 may monitor, estimate or predict the congestion of the network 104,bandwidth utilization or available bandwidth of the network 104. Thedata transform model 440 may include any type and form of modelrepresentation, such as data, data structures and/or executableinstructions. Data transfer model 440 may store the latest statisticsand information used to determine the optimal amount of data orinformation to be transmitted and optimal timing to transmit the amountin order to fully utilize available resources and not create anyadditional delays by sending too much data too quickly. Data transfermodel 440 may comprise algorithms to determine the amount of interactivedata 411 and bulk data 410 to be transmitted and at what time based onthe latest updated information, values or statistics, as updated bymessages received from the model of the receiver. The receiver,transmitting the messages comprising the updated values or statistics,may be the receiver receiving the interactive and bulk data 410 and 411.The receiver may also be the appliance 200, also referred to as theintermediary, traversing the data transmitted between the sender and thereceiver. The appliance 200 may comprise the receiver's model andcollect the statistics, such as the bandwidth, compression ratio of adata compressed or the backlog value to update the data transfer model440. In some embodiments, data transfer model 440 receives messages withupdated values or statistics from the model from the appliance 200traversing the information transmitted and from the receiver receivingthe information transmitted. The data transfer model 440 may utilizemessages from both, the model of the appliance 200 and the model of thereceiver, to update the values, metrics and statistics of the datatransfer model 440 with the latest values, metrics or statistics.

For example, in a system depicted by FIG. 4, a sender may transmit viathe appliance 200 to the receiver data which comprises interactive data410 and bulk data 411. The network 104, or a connection between thesender and the receiver, may support an optimal amount of transmissionwhich would utilize the available resources of the network to themaximum but not created additional delays and backlog. The networkoptimizer 420 and the data transfer model 440 may estimate the optimalamount of transmission based on the data transfer model 440, which mayalso be referred to as the model of the network optimizer 420. The datatransfer model 440 may determine the optimal amount of data to betransmitted and the optimal timing for transmitting the optimal amountof data. The data transfer model 440 determines the optimal amount andthe optimal timing based on the latest values, metrics and statistics.The values, metrics and statistics used for determining may be anyinformation relating the status of the resources on the network, suchas: the bandwidth of the connection between the sender and the receiver,bandwidth between the sender and the appliance 200, bandwidth betweenthe appliance 200 and the receiver, mean bandwidth value between thesender and the receiver, standard deviation of the bandwidth between anytwo of the sender, appliance 200 and the receiver, compression ratio ofdata compressed by the appliance 200, the backlog value of an amount ofdata to be transmitted as stored in the queue of the appliance 200 andthe backlog value of the data to be sent by the sender. The values,metrics and statistics of the data transfer model 440 may change withtime and thus may become outdated, resulting in the amount of data to betransmitted and the timing as determined by the model to be not optimal.

In order to compensate for the outdated values, metrics and statistics,the intermediary model 455 of the appliance 200 may transmit to the datatransfer model 440 the latest and the most up to date values, metricsand the statistics via one or more messages from either the receiver,the appliance 200, or both. The data transfer model 440 updates thevalues, metrics and statistics based on the values, metrics andstatistics transmitted within any number of messages. The messagestransmitted between the models may include any information relating thestate of data or state of resources of the network. The data transfermodel 440 may receive the message with updated metrics, values andstatistics and metrics and may determine the new amount of data to betransmitted and the new timing of the new amount of data to betransmitted. The new amount and the new timing are determined using thelatest metrics, values and statistics and are therefore optimal orcloser to being optimal since the information used for determination aremore up to date. Data transfer manager 430, may receive the new amountand the new timing and may transmit, via the appliance 200 to thereceiver, a new amount of data 410 or 411 as determined by the newamount and at the time determined by the new timing. The transmissionmay thus be optimal until the situation of the network or networkresources changes again. The appliance 200 and the receiver may keepmonitoring the network and keep updating their models as necessary inorder to update the data transfer model 440 for the futuretransmissions.

Sometimes, the data transfer model 440 may be used to calculate theamount of data to be sent over the network and the timing of amount ofdata to be transferred. Data transfer model 440 may also be used todetermine which portions of the amount to be transferred will be made upof interactive data 410 or bulk data 411. In some embodiments, the datatransfer model determines which data to be transmitted based on thebacklog of the data in the queue of the appliance 200 waiting to betransmitted from the appliance 200 to the receiver.

FIG. 4 also illustrates communication of data packets 480 between thesender and a receiver, such as the appliance 200. The data packets arelabeled 480A-N where N may stand for any number or symbol. Data packetsmay be any chunks, groups or amounts of data or information organizedusing any format utilized by the system. In some embodiments, datapackets 480 are sequences of bytes comprising a header and a body. In aplurality of embodiments, data packets 480 comprise an identifieruniquely identifying each data packet from any other data packetcommunicated via the system. In a plurality of embodiments, data packets480 are used as a part of a TCP communication. In some embodiments, datapackets are compressed data packers, payloads or groups of information.In certain embodiments, data packets 480 may comprise packets and/orpayloads of same size. In a plurality of embodiments, a data packet 480Amay have a different size than another data packet 480B. In someembodiments, a data packet 480 comprises an instruction. In a pluralityof embodiments, a data packet 480 comprises an information, a value or adata. In some embodiments, a data packet 480 comprises a command. In anumber of embodiments, a data packet 480 comprises a user data or apayload. In some embodiments, a data packet 480 comprises an errordetection code or an error detection mechanism. In a plurality ofembodiments, a data packet 480 is a formatted group of informationcommunicated via a TCP/IP network communication or any other networkcommunication protocol.

FIG. 4 also illustrates appliance 200, already introduced earlier, andshown communicating with the sender and another appliance 200, client102, or server 106 (e.g., receivers) which receive the transmission fromthe sender. In some embodiments, appliance 200 comprises any number ofsubcomponents introduced earlier, such as the packet processing engine240, the flow controller 220 and the compression engine 238. FIG. 4illustrates a number of embodiments wherein the appliance 200 comprisesthe intermediary model 455 and the bandwidth measurer 450. In someembodiments, the network system depicted by FIG. 4 may be such that thespeed of the network transmissions between the sender and the appliance200 is substantially faster than the speed of the network transmissionsbetween the appliance 200 and the receiver, wherein the receiver may beanother appliance 200, a client 102 or a server 106.

Compression engine 238, in addition to aforementioned features andembodiments, may also comprise other features or embodiments such as themeans to perform high performance network compression. In someembodiments, compression engine 238 compresses data using a compressionmethod utilizing a plurality of compressed data packets wherein onecompressed data packet of the plurality of compressed data packets has acompression ratio different than another compressed data packet of theplurality of data packets. In a number of embodiments, a compressionengine 238 stores a compression ratio of each individual compressedpacket of a plurality of packets. In some embodiments, the storedcompression ratio information of each individual compressed data packetis sent to the sender or the data transfer model 440. In someembodiments, the compression engine shares information or instructionswith other units or components in the system such as the systemillustrated in FIG. 4 to improve the throughput of the information orthe efficiency of the transmissions. In certain embodiments, thecompression engine 238 is sharing information and communicating with thesender or some subcomponents or subsystems of the sender.

The intermediary model 455 may be any device, software, algorithm orapplication used to model network activity, bandwidth utilization,transmission rates and compression rates related to the intermediary. Inone embodiment, the intermediary model may predict an optimal or desiredamount of data to be sent over the network and the timing of the data tobe sent based on a number of values used for monitoring the state of thenetwork. The intermediary model 455 may include any type and form ofmodel representation, such as data, data structures and/or executableinstructions. In a number of embodiments, intermediary model 455 is anindependent device sharing information with appliance 200. In aplurality of embodiments, intermediary model 455 is a softwareapplication. In certain embodiments, intermediary model 455 is anappliance. In a plurality of embodiments, intermediary model 455 is apart of the compression engine 238, and in some other embodiments theintermediary model 455 comprises the compression engine 238. In someembodiments, intermediary model 455 is a part of the flow controller,and in some other embodiments the intermediary model 455 comprises theflow controller.

In some embodiments, intermediary model 455 comprises functions,operations or logic to model the transmission rates, compression ratesand bandwidth utilization of one or more intermediaries. In oneembodiment, intermediary model 455 is an algorithm using a statisticalapproach and a set of most recently updated values to predict a maximumor otherwise predetermined amount of data that can be transmitted overthe network without creating additional transmission delays. In someembodiments, intermediary model 455 determines the amount of data to betransmitted over the network 104, such as via the intermediary, and thetiming of the data to be transmitted based on the most recently updatedbandwidth value. In a plurality of embodiments, intermediary model 455determines the amount of data to be transmitted over the network 104 andthe timing of the data to be transmitted based on: the most recentlyupdated compression ratio value of a compressed data packet 495,compression ratio values of a plurality of compressed data packets 495or a difference between the compression ratio values of two or morecompressed data packets 495. In some embodiments, intermediary model 455determines the amount of data to be transmitted over the network 104 andthe timing of the data to be transmitted based on the most recentlyupdated backlog value.

Bandwidth measurer 450 may be any bandwidth measuring device, function,operation or logic for determining bandwidth between two entities, suchas the appliance 200 and a receiver. In some embodiments, bandwidthmeasurer 450 performs any type and form of ping command. In someembodiments, bandwidth measurer 450 determines an availability,idleness, throughput or utilization of network bandwidth. In anotherembodiment, bandwidth measurer 450 determines any type of round-triptime between two entities. The bandwidth measurer 450 may use any typeand form of round-trip time computation or calculation to measurebandwidth. For example, the measurer 450 may use the following type ofbandwidth measurement:

Bandwidth=Factor*MTU/(Round Trip Times*sqrt(Packet Loss)), where thefactor may be for example 1.3

As illustrated by the above equation, bandwidth may be determined basedon packet loss, round trip times and/or packet size adjusted by apredetermined factor. Although a measurement of bandwidth using theabove equation is described, other derivatives of this request using anycombination of factors, maximum transmission unit (MTU), round triptimes and packet loss may be used.

In some embodiments, the bandwidth measurer 450 determines a number ofbytes transferred between two entities, such as client and intermediary,intermediary and server or client and server. The bandwidth measurer 450determines the number of transferred bytes over a time period, such asevery second or bytes transferred per second. In one embodiment, thebandwidth measurer 450 determines an average number of bytes transferredper the time period, such as per second. In some embodiments, thebandwidth measurer 450 measures the number of bytes transmitted by theintermediary. In other embodiments, the bandwidth measurer 450 measuresthe number of bytes received by the intermediary. In one embodiment, thebandwidth measurer 450 measures the number of bytes received andtransmitted by the intermediary. In yet another embodiment, thebandwidth measurer 450 measures the number of bytes transmitted by theone or more servers. In other embodiments, the bandwidth measurer 450measures the number of bytes transmitted by one or more clients 102. Inother embodiments, the bandwidth measurer 450 measures bandwidth basedon the number of packets on a queue waiting to be transmitted. In someembodiments, the bandwidth measurer 450 determines bandwidth usage viathe transition of a queue of network packets from empty to non-empty andvice-versa.

In a number of embodiments, bandwidth measurer 450 measures bandwidth bya method of bandwidth measurement including the step of transmitting,from a sender or a receiver, a pair of uniquely marked data packets 480or compressed data packets 495 over the network along with valuesindicating the time the time of the transmission of each uniquely markeddata packet 480 or compressed data packet 495. The method of bandwidthmeasurement also may comprise the step of receiving the pair of uniquelymarked data packets 480 or compressed data packets 495, transmitted bythe sender or the receiver, and marking the values comprising the timingof arrival of each data packet 480 or compressed data packet 495 asreceived by the receiver or the sender. In some embodiments, thebandwidth measurement method also uses the marked values indicating thetime of the transmission and the values comprising the timing of arrivalto establish the bandwidth of the network. In a number of embodiments,the method of bandwidth measurement also subtracts the differencebetween the timing of arrival of each uniquely marked data packets 480or compressed data packets 495 sent using the timing difference betweeneach of the uniquely marked data packet or compressed data packetsreceived. In a plurality of embodiments, uniquely marked data packets480 are compressed.

In a number of embodiments, a bandwidth measurer 450 comprises anappliance. In certain embodiments, a bandwidth measurer 450 is a part ofthe compression engine 238. In a plurality of embodiments, a bandwidthmeasurer 450 is be a part of the flow controller 220. In someembodiments, a bandwidth measurer 450 is a unit or a device independentfrom the network optimization engine 250, while in some embodiments thebandwidth measurer 450 is a part of the network optimization engine 250.In a plurality of embodiments, a bandwidth measurer 450 is a unit or adevice independent from the appliance 200. In specific embodiments,bandwidth measurer 450 communicates the latest or the most recentlyupdated bandwidth value to the intermediary model 450. In someembodiments, bandwidth measurer 450 communicates the latest or the mostrecently updated value of the bandwidth to the sender, the 420 networkoptimization engine or 440 data transfer model. In a number ofembodiments, a bandwidth measurer 450 uses a plurality of bandwidthdeterminations to come up with a bandwidth value which will be used bythe intermediary model 455.

Compressed data packets 495 may be any type and form of compressed orreformatted groups of data comprising a portion of, one of, or aplurality of 480 data packets. Compressed data packets 495 comprise anynumber of one or more data packets 480. Each of the one or morecompressed data packets may be compressed using the same compressionscheme or different compression scheme. Each of the one or morecompressed data packets may be compressed in a manner resulting in thesame compression ratio or different compression ratios. In someembodiments, a first compressed data packet 495 out of a plurality ofcompressed data packets 495 comprises a number of data packets 480different than a number of data packets 480 comprised by a secondcompressed data packet 495 of a plurality of compressed data packets495. In some embodiments, a first compressed data packet 495 out of aplurality of compressed data packets 495 comprises a substantiallysimilar number of data packets 480 in comparison to a number of datapackets 480 comprised by a second compressed data packet 495 of aplurality of compressed data packets 495. In some embodiments, a firstcompressed data packet 495 out of a plurality of compressed data packets495 comprises a compression ratio that is different than a compressionratio comprised by a second compressed data packet 495 of a plurality ofcompressed data packets 495. In a number of embodiments, a firstcompressed data packet 495 out of a plurality of compressed data packets495 comprises a compression ratio that is substantially similar to acompression ratio comprised by a second compressed data packet 495 of aplurality of compressed data packets 495.

The receiver is illustrated on the right side of the FIG. 4. Thereceiver may be any device, an appliance or any system capable ofreceiving information. In some embodiments the receiver is an appliance200. In a number of embodiments, the receiver is a client 102. In aplurality of embodiments, the receiver is a server 106. In a number ofembodiments, the receiver may be any combination of the appliance 200,server 106 or the client 102. The receiver may comprise any and all offeatures and embodiments of a server 106, a client 102 and an appliance200.

Any embodiment of any feature illustrated in FIG. 4 or in thedescription relating to FIG. 4 may be combined with any other embodimentof any other feature illustrated elsewhere in FIG. 4 or in thedescription relating to FIG. 4 or in any other illustration in thepresent disclosure or in any portion of the text of the presentdisclosure.

Referring now to FIG. 5, an embodiment of steps of a method 500 forimplementing an efficient data flow control by an intermediary model 455are illustrated. The steps of the method 500 may be implemented in anyorder despite how they are ordered in the illustration. In someembodiments, some steps of the method 500 are combined with other stepsor may even be omitted from the method. Furthermore, the decision stepsare also presented by the illustration as a part of the method. Thesteps are performed by the system such as the one introduced by FIG. 4,tailored to the control of the amount of data to transmit by the sender.A number of embodiments in the method utilize recently updatedinformation to make a determination of the amount of the data to betransmitted and the timing of transmission. In some embodiments, themethod utilizes not recently updated information to make a determinationof the amount of the data to be transmitted and the timing of thetransmission.

In brief overview, at step 505 of method 500, a sender transmits to afirst intermediary a first set of values and determinations for dataflow control of the data sent by the sender. At step 510, the firstintermediary establishes a next set of values and determinations fordata flow control of the data sent by the sender. At step 515, thesender determines if the first set of values and determinationssubstantially different from the next set of values and determinations.At step 520, the sender receives the next set of values anddeterminations from the first intermediary. At step 525, a data transfermanager determines a size of a next portion of data queued fortransmission and a time for transmitting the portion of data queued.

In further details, step 505 involves a sender transmitting to a firstintermediary a first set of values and determinations for data flowcontrol of the data sent by the sender. In some embodiments, the senderin step 505 is the sender described in FIG. 4. The first intermediarydescribed in step 505 may be any device, system, structure or anappliance intercepting the data transmitted by the sender to thereceiver and performing an operation on the data transmitted, changingthe data transmitted, or affecting the flow of the data transmitted. Insome embodiments, the first intermediary may be any system, device or astructure intercepting data between a sender transmitting data and areceiver receiving the transmitted data. In some embodiments, a firstintermediary is an appliance 200 or appliance 200′.

A first set of values and determinations described in step 505 maycomprise any number of values, constants, functions or data structurescomprising information which may be relevant to the state of the networkor the available resources of the network over which the data iscommunicated. These first set of models may be established or determinedvia any of the models described herein. In some embodiments, a first setof values and determinations comprise a value of a bandwidth between twoappliances on a network. In a number of embodiments, a first set ofvalues and determinations comprise a value relating a bandwidthdetermination of a bandwidth of the network or of the portion of anetwork over which the data is communicated. In some embodiments, afirst set of values and determinations comprise a value relating to acompression of the data being communicated. In a plurality ofembodiments, a first set of values and determinations comprise a valuerelating to a compression ratio of the data being transmitted orcommunicated. In a number of embodiments, a first set of values anddeterminations comprise a value relating to a backlog of the datatransmitted on the network. In some embodiments, a first set of valuesand determinations comprise a value relating to specific time when anext amount of data should be transmitted. In a number of embodiments, afirst set of values and determinations comprise a value in the form ofan integer. In a plurality of embodiments, a first set of values anddeterminations comprise a value in the form of a float, a character or asymbol. In certain embodiments, a first set of values and determinationscomprise an array of values. In some embodiments, a first set of valuesand determinations comprise a data structure comprising a variety ofvalues or arrays comprising values. In a number of embodiments, a firstset of values and determinations comprise a value relating to a specificamount of data to be transmitted by the sender or by the firstintermediary, an appliance 200, a client 102 or a server 106. In someembodiments, a first set of values and determinations comprise a valuerelating to an amount of time a next transmission by a sender, a client102 or a server 106 should be delay by. In certain embodiments, a firstset of values and determinations is related to a level of traffic of anetwork or a congestion of a network over which the data is transmitted.

At step 510, the first intermediary establishes a next set of values anddeterminations for data flow control of the data sent by the sender.This may be performed via any of the models described herein. In someembodiments, the first intermediary may be the first intermediaryindicated from step 505. In some embodiments, the first intermediary maybe a different first intermediary having the same features andembodiments as the first intermediary in step 505. In a plurality ofembodiments, a next set of values and determinations is the first set ofvalues and determinations as described above. In a number ofembodiments, a next set of values and determinations comprise any andall embodiments of the first set of values and determinations describedabove. In some embodiments, a next set of values and determinationscomprise any and all of features, descriptions, forms as described inthe embodiments of the first set of values and determinations. In aplurality of embodiments, a next set of values and determinations issubstantially similar in structure and form of the information comprisedto the first set of values and determinations. In a plurality ofembodiments, a next set of values and determinations is substantiallydifferent in structure and form of the information comprised to thefirst set of values and determinations. In some embodiments, the valuesand determinations comprised in the first set of values anddeterminations have a format similar to the one used in the next set ofvalues and determinations. In some embodiments, step 510 may occur inresponse to another step in the method 500. In some embodiments, step510 may occur independently of any other step in the method 500.

At step 515, a decision is made to determine whether or not the firstset of values and determinations is substantially different from thenext set of values and determinations. This may be performed via any ofthe models described herein. In a number of embodiments, step 515 iscompleted by the sender. In some embodiments, step 515 is completed byan appliance 200 or a first intermediary. In some embodiments,“substantially different” in step 515 indicates anything other thanidentical from the value used to be compared to. In a plurality ofembodiments, “substantially different” in step 515 indicates differentby more than a predetermined threshold value from the value beingcompared to. In a number of embodiments, “substantially different” instep 515 indicates different as determined by an algorithm or a functionfrom the value being compared to. In some embodiments, “substantiallydifferent” in step 515 indicates different more than a predeterminedpercentage from the value being compared to, or more than a specificpercentage from the average value being compared to.

In a number of embodiments, a predetermined function, application, or avalue may be established or utilized to help determine what asubstantial difference between two values compared is. This may beperformed via any of the models described herein. In some embodiments,any difference between a first value of a first set of values anddeterminations and a next value, indicating or relating to a sameparameter or feature as the first value of a next set of values anddeterminations results in the first set of values and determinations andthe next set of values and determinations being substantially different.In a plurality of embodiments, a difference of more than a predeterminedvalue, a predetermined difference in percentage or a predetermined ratiobetween a first value of a first set of values and determinations and anext value, indicating or relating to a same parameter or feature as thefirst value of a next set of values and determinations results in thefirst set of values and determinations and the next set of values anddeterminations being substantially different. In some embodiments, step515 occurs in response to another step in the method 500. In a number ofembodiments, step 515 occurs in response to either step 505 or step 510,or both step 505 and step 510. In some embodiments, step 515 occursindependently of any other step in the method 500.

At step 520, the sender receives the next set of values. This may beperformed using any of the models described herein and sending and/orreceiving any type and form of messages. In some embodiment, if theresult of the step 515 is that the first set of values anddeterminations and the next set of values and determinations aresubstantially different, the sender receives the next set of values anddeterminations from the first intermediary. In some embodiments thesender receives the next set of values and determinations from the firstintermediary on a regular periodic basis that may be independent fromany other step in the method. In some embodiments, step 520 may occur inresponse to the step 515, step 505 or step 510, or in response to acombination of any two or all three of steps 505, 510 and 515. In someembodiments, step 520 may occur independently of any other step in themethod 500.

At step 525, a data transfer manager determines a size of a next portionof data queued for transmission and a time for transmitting the portionof data queued. In some embodiments, the data transfer manager of step525 is a data transfer manager 430. In certain embodiments, a datatransfer manager in step 525 may indicate a data transfer manager in anyof the components discussed in FIG. 4. In a number of embodiments, thesize of a next portion of data queued for transmission and the time fortransmitting the portion of data queued relates to the interactive data410. In a plurality of embodiments, the size of a next portion of dataqueued for transmission and the time for transmitting the portion ofdata queued relates to the bulk data 411. In some embodiments, the sizeof a next portion of data queued for transmission and the time fortransmitting the portion of data queued relates to a combination of theinteractive data 410 and the bulk data 411. In certain embodiments, thesize of a next portion of data queued for transmission and the time fortransmitting the portion of data queued relates to the data sent by asender, a client 102 or a server 106 to a first intermediary or anappliance 200. In plurality of embodiments, the size of a next portionof data queued for transmission and the time for transmitting theportion of data queued relates to the data sent by a sender, a client102 or a server 106 to a receiver, a client 102 or a server 106.

It should be expressly understood that any embodiment or a featureillustrated in any figures or in the text relating to any figures may becombined with any other embodiment or any other feature illustratedelsewhere in other figures or other portions of the text.

Referring now to FIG. 6, a number of embodiments of a method 600 for anefficient data flow control by the network optimizer or data flowmanager are illustrated. The steps of the method 600 may be implementedin any order. In some embodiments, some steps of the method 600 arecombined with other steps or may even be omitted from the method.Furthermore, the decision steps made by the method are also illustratedin FIG. 6. The steps may be performed by the components of a system suchas the system presented in FIG. 4, tailored to the control of the amountof data to transmit by the sender. FIG. 6 illustrates a number ofembodiments wherein the method utilizes available updated information tomake determination of the amount of the data to be transmitted by thesender and the timing to transmit the data.

In brief overview, at step 605 of method 600, establishing by thenetwork optimizer and/or data transfer manager a current threshold time,a current backlog time, a next frame capture time and a next thresholdtime. In a plurality of embodiments, the current threshold time, thecurrent backlog time, the next frame capture time and the next thresholdtime are used for controlling the flow of data. Sometimes the currentthreshold time, the current backlog time, the next frame capture timeand the next threshold time are referred to as method 600 values. Themethod 600 values may be of any format or type. In some embodiments, themethod 600 values are integer values. In some embodiments, the method600 values are character values, float values or long character values.In a number of embodiments, the method 600 values are arrays comprisingany number of values of any type. In some embodiments, the method 600values comprise a data structure comprising any type of values orarrays. In a plurality of embodiments, the method 600 values arefunctions with respect to time or to an event. In a number ofembodiments, the method 600 values may be received from anothercomponent such as an appliance 200, a client 102, server 106, or anyother unit or a system. In some embodiments, the method 600 values maybe the first set of values and determinations from method 500 or thenext set of values and determinations from the method 500. In certainembodiments, the method 600 values may comprise any and all embodimentsor features from the first set of values and determinations from method500 or the next set of values and determinations from the method 500.

Step 610 describes a decision making process wherein the system answersthe question whether the current threshold time is greater than thecurrent backlog time. In some embodiment, the current threshold timevalue is compared to the current backlog time value using a logic unitsuch as a logic comparator. In a number of embodiments, the currentthreshold time value is compared to the current backlog time using amicroprocessor or a central processing unit. In a plurality ofembodiments, step 610 is performed by a network optimizer 420, a datatransfer manager 430 or a data transfer model 440. In a number ofembodiments, step 610 is completed by the sender. In some embodiments,step 610 is performed by an appliance 200 or a first intermediary. Insome embodiments, the comparison in step 610 involves a tolerable rangewherein no action may be taken if the two values are different withinthe tolerable range. In a number of embodiments, the tolerable range isa value or a function of a ratio or a percentage. In some embodiments,if the result of step 610 is that the current threshold time is notgreater than the current backlog time no action is taken. In a number ofembodiments, if the result of step 610 is that the current thresholdtime is not greater than the current backlog time a step 615 istriggered. In some embodiments, if the result of step 610 is that thecurrent threshold time is greater than the current backlog time noaction is taken. In a number of embodiments, if the result of step 610is that the current threshold time is greater than the current backlogtime a step 615 is triggered. In some embodiments, step 610 occurs inresponse to another step in the method 600. In a number of embodiments,step 610 occurs independently of any other step in the method 600.

Step 615 describes a decision making process wherein the system answersthe question whether the next frame capture time is less than thecurrent threshold time plus the next threshold time. In someembodiments, the current threshold time and the next threshold time areadded before being compared to the next frame capture time. In someembodiments, the current threshold time and the next threshold time arenot added before being compared to the next frame capture time. In someembodiments, the comparison in step 615 involves a tolerable rangewherein no action may be taken if the two values are different withinthe tolerable range. In a number of embodiments, the tolerable range isa value or a function of a ratio or a percentage. In some embodiments,if the result of step 615 states that the next frame capture time isless than the current threshold time plus the next threshold time step620 is triggered. In a number of embodiments, if the result of step 615states that the next frame capture time is less than the currentthreshold time plus the next threshold time step 625 is triggered. In aplurality of embodiments, if the result of step 615 states that the nextframe capture time is equal to or greater than the current thresholdtime plus the next threshold time step 620 is triggered. In someembodiments, if the result of step 615 states that the next framecapture time is equal to or greater then than the current threshold timeplus the next threshold time step 625 is triggered. In some embodiments,step 615 occurs in response to another step in the method 600. In anumber of embodiments, step 615 occurs independently of any other stepin the method 600.

Step 620 describes selecting an amount of bulk data 411 fortransmission. In some embodiments, a sender may complete step 620. In anumber of embodiments, step 620 is completed by a network optimizer 420or a data transfer model 430. In a plurality of embodiments, an amountof data is determined by a network optimizer 420, a data transfermanager 430 or a data transfer model 440. Amount of bulk data 411 may beany amount of data expressed in bytes or any other units. In someembodiments, an amount of bulk data 411 includes a whole instruction ora task. In a number of embodiments, an amount of bulk data 411 includesprinting instructions or a file to be printed. In a plurality ofembodiments, an amount of bulk data 411 comprises a graphicalrepresentation of a feature or a shot of a computer screen. In someembodiments, an amount of bulk data 411 comprises a data file, datavalues, instructions, commands, pictures, videos or audio files, or anyother information.

Step 625 recites initiate a next frame capture. In some embodiments, asender completes the step 625. In a number of embodiments, step 625 iscompleted by a network optimizer 420 or a data transfer model 430. In aplurality of embodiments, a next frame capture is initiated by a networkoptimizer 420 or a data transfer manager 430. A next frame capture maycomprise any amount of interactive data 410 or bulk data 411. In someembodiments, a next frame capture comprises any amount of interactivedata 411 determined by system. In a plurality of embodiments, a nextframe capture comprises a predetermined set of data planned fortransmission on the next available opportunity.

Any of the embodiments of methods depicted in FIGS. 5 and 6 may have anyof the steps performed via sending of message and updated values betweenmodels.

E. Allocation of Bandwidth

Referring now to FIG. 7, a block diagram is illustrated showingembodiments of a system for allocation of bandwidth credit by anintermediary 200. The illustration shows data transmitted from a senderto a receiver, via an intermediary 200, which may also be referred to asan appliance 200. The sender and the receiver may either be a client 102or a server 106. The intermediary 200 intercepts the data between thesender and the receiver, the data being presented by data packets 480and compressed data packets 495. The intermediary 200 may compress datapackets 480 sent by the sender into compressed data packets 495transmitted to the receiver using any compression methods or anycompression ratios. FIG. 7 illustrates embodiments utilizing only oneappliance 200 deployed between the sender and the receiver although inmany applications, there may be a plurality of appliances 200 deployedbetween the sender and the receiver.

In a brief overview, FIG. 7 illustrates a sender sending data to areceiver via an intermediary 200. In some embodiments, data transmittedby the sender may be organized into the data packets 480. In someembodiments, the data transmitted by the sender may comprise datapackets 480 along with other additional data formed or organized in waysother than data packets 480. In many embodiments, data packets 480 maydefine any data transmitted by the sender. The data packets 480 may bereceived by the intermediary 200. In addition to the aforementioned flowcontroller 220, compression engine 238 and bandwidth measurer 450, theappliance 200 may further comprise a bandwidth allocator 710 and abandwidth monitor 720. The intermediary 200 may compress the data fromthe sender into compressed data packets 495. The compressed data packets495 may be sent or transmitted to the receiver or a plurality ofreceivers. The receiver, or the plurality of receivers, may be anynumber of clients 102, servers 106, appliances 200, any of which mayreceive compressed data packets 495 compressed by the appliance 200.

In many embodiments, the sender may generate data and transmit thegenerated data in the form of a stream of data packets 480. In someembodiments, the sender may receive data from another sender and forwardthe data to the appliance 200. The sender may communicate with theapplication 200 transmitting the information back and forth. Theinformation transmitted may comprising data packets 480. Data packets480, in some embodiments, further comprise any number of signals,instructions, digital or analog data, digital data bits, electricalsignals, optical signals, optical pulses, or any signals detectable bythe sender or the receiver.

The appliance 200 illustrated in FIG. 7 may comprise a flow controller220. The flow controller 220 may determine the rate of transmission ofthe data transmitted by the sender or the receiver. In a number ofembodiments, the flow controller 220 determines the bandwidth usage ofthe sender or the receiver. In many embodiments, the flow controller 220determines the bandwidth credit of the sender or the receiver. The flowcontroller 220 may also determine a difference between the rate oftransmission of the sender or the receiver and the bandwidth usage ofthe sender or the receiver. The flow controller 220 may also determine adifference between the rate of transmission of the sender or thereceiver to determine a bandwidth credit for the sender or the receiver.In a number of embodiments, the flow controller 220 determines that adifference between the rate of transmission of the sender and thebandwidth usage of the sender falls below or above a predeterminedthreshold of the bandwidth credit. In some embodiments, the flowcontroller 220 determines that a difference between the rate oftransmission of the sender and the bandwidth usage of the sender fallswithin a predetermined threshold range.

The bandwidth credit may be any amount of data a sender may transmit. Insome embodiments, the bandwidth credit may be an amount of bytes,megabytes, gigabytes or terabytes of data a sender may transmit over aperiod of time. In a number of embodiments, the bandwidth credit may beany amount of data a receiver may receive over a period of time. In someembodiments, the bandwidth credit of a sender or a receiver is notbounded by a period of time. Sometimes, a bandwidth credit is an amountof data, in bytes or megabytes for example, which a sender may send in aone-time transmission. In some embodiments, a bandwidth credit is anamount of data in any units of data a sender may transmit in any numberof transmissions. Bandwidth credit, in some embodiments, may be anamount of bandwidth a sender, an appliance or a receiver may receive ortransmit over a predetermined time period, or even sometimes independentfrom any time period.

The compression engine 238, illustrated by FIG. 7, may perform anycompression of data or reformatting of data which traverses theappliance 200. In some embodiments, the compression engine 238compresses the data of the appliance 200 using compression ratios whichvary between from a sections of a data stream to a section of a datastream. For example, some groups of data packets 480 may be compressedusing a compression ratio different from the compression ratios of othergroups of data packets 480. In some embodiments, compression engine 238comprises any functionality of a flow controller 220, a bandwidthmeasurer 450, or any other functionality of an appliance 200. In anumber of embodiments, the compression engine 238 compresses the datatransmitted by a sender using a specific compression ratio or a specificcompression format. Sometimes, the compression format or the compressionratio used by the compression engine 238 is identified by the sender. Insome embodiments, the appliance 200 or the compression engine 238assigns a compression ratio used for compressing data transmitted by thesender based on identification of the sender. The compression engine 238may compress data transmitted by the sender or the receiver by using analgorithm compressing data packets 480 from the sender into compresseddata packets 495. Some compressed data packets 495 compressed by thecompression engine 238 may have compression ratios different from thecompression ratios of other compressed data packets 495 compressed bythe compression engine 238. Compression engine 238, in some embodiments,monitors the compression ratios of each compressed data packets 495 anddata packets 480. In some embodiments, the compression engine 238maintains statistics relating the ratio of size of data packets 480 andcompressed data packets 495 or compression ratios relating each of thedata packets 480 or compressed data packets 495.

Bandwidth measurer 450, illustrated by FIG. 7, may be any device, unitor a function measuring bandwidth between any devices on a network 104,such as senders, receivers or appliances 200. In many embodiments, thebandwidth measurer monitors the bandwidth of the network 104 or over aportion of the network 104. In some embodiments, bandwidth measurer 450measures the bandwidth between two or more appliances, senders orreceivers on a network 104. In a number of embodiments, bandwidthmeasurer 450 measures the bandwidth between a sender and an appliance200. In many embodiments, the bandwidth measurer 450 measures thebandwidth between the receiver and the appliance 200. The bandwidth 450may measure the bandwidth between two or more appliances, clients orservers on the network, in the upload or the download directionsseparately. In some embodiments, bandwidth measurer 450 measures anaverage bandwidth usage over a period of time between a sender and anappliance 200. In many embodiments, bandwidth measurer 450 measures theamount of data transmitted between two devices on a network anddetermines the bandwidth between the two devices using the amount of thedata transmitted and the amount of time it took to transmit the data.The bandwidth measurer 450 may measure an average bandwidth credit usedby a sender or a receiver over a period of time. The bandwidth measurer450 may also measure an average bandwidth usage over a period of timebetween a receiver and an appliance 200. The bandwidth measurer 450 mayalso measure an average bandwidth credit for a sender or a receiverunbounded by or independent from any period of time the bandwidth creditis to be used for. The average bandwidth usage may be updated after eachperiod of time passes, thus keeping the average bandwidth usage updated.In some embodiments, the bandwidth measurer may measure the availablebandwidth or the bandwidth unused by traffic, between any one of asender and a receiver, sender and an appliance 200 or an appliance 200and a receiver, or any other device or a group of devices on a network.

Bandwidth allocator 710 may be any device, function, component or unitfor allocating bandwidth or establishing a bandwidth for any entity ordevice such as a sender, a receiver or an appliance 200. The bandwidthallocation may be in a form of a credit, subscription or annuity ofbandwidth allocation in any type and form of units. Bandwidth allocator710 may comprise any circuitry, software, algorithms, functions ordevices for determining an amount of bandwidth to be allocated to anyone of a sender, receiver or an appliance 200. Bandwidth allocator 710may comprise any type and form of software, application, library,service, script, process, task or set of executable instructions. Inmany embodiments, bandwidth allocator 710 comprises any functionality ofa bandwidth measurer 450. In some embodiments, bandwidth allocator 710comprises a bandwidth measurer 450. In some embodiments, bandwidthmeasurer 450 comprises a bandwidth allocator 710 or comprises anyfunctionality of a bandwidth allocator 710.

In some embodiments, bandwidth allocator 710 receives informationrelating to bandwidth measurement from a bandwidth measurer andallocates bandwidth in response to the received information. In a numberof embodiments, bandwidth allocator receives information from a flowcontroller 220, compression engine 238, bandwidth monitor 720, a sender,a receiver or an appliance 220 and determines an amount of bandwidth tobe allocated in response to the received information. In a variety ofembodiments, bandwidth allocator 710 determines or establishes an amountof bandwidth to be allocated to any one of a sender, receiver or anappliance 200 using bandwidth statistics or bandwidth measurements, orany bandwidth related information from any one of bandwidth measurer450, bandwidth monitor 720, flow controller 220 or any other componentof an appliance 200. In a number of embodiments, bandwidth allocator 710determines or establishes an amount of bandwidth to be allocated to anyone of a sender, receiver or an appliance 200 using bandwidth statisticsor bandwidth measurements or any bandwidth related information from asender or a receiver. In some embodiments, bandwidth allocator 710 usesbandwidth usage statistics or measurements to allocate the bandwidth toany one of a sender a receiver or an appliance 200. In a plurality ofembodiments, bandwidth allocator 710 allocates a bandwidth amount to asender wherein the sender can transmit an amount of information or dataidentified by the bandwidth allocated within a specified amount of time.In some embodiments, bandwidth allocator 710 allocates a bandwidthamount to a sender to transmit an amount of information or dataidentified by the bandwidth allocated regardless of the timing of thetransmission. In some embodiments, the bandwidth allocated by thebandwidth allocator 710 may be used by the sender to send a one timetransmission whose bandwidth amount does not exceed the amount definedby the bandwidth allocated. In some embodiments, the bandwidth allocatedby the bandwidth allocator 710 may be used by the sender to send aplurality of transmissions which use bandwidth amounts equal to or lessthan the allocated bandwidth amount.

Bandwidth monitor 720 may be any device, function, component, unit orpiece of software or hardware monitoring bandwidth between any two ormore devices, such as senders, receivers and appliances 200, on anetwork. In some embodiments, bandwidth monitor 720 comprises anycircuitry, logic components, hardware, software or a combination ofsoftware and hardware for monitoring bandwidth on a network. Bandwidthmonitor 720 710 may comprise any type and form of software, application,library, service, script, process, task or set of executableinstructions. In some embodiments, bandwidth monitor comprises any oneof, or any combination of a flow controller 220, compression engine 238,bandwidth measurer 450 and bandwidth allocator 710. In a number ofembodiments, bandwidth monitor 720 comprises any functionality of anyone or any combination of a bandwidth allocator 710, bandwidth measurer450, compression engine 238 and a flow controller 220. In someembodiments, any one of a flow controller 220, compression engine 238,bandwidth measurer 450, bandwidth allocator 710 or bandwidth monitor 720comprises any functionality, any features or any processes and functionsof any one of, or any combination of a flow controller 220, compressionengine 238, bandwidth measurer 450, bandwidth allocator 710, bandwidthmonitor 720, appliance 200, sender and a receiver.

In some embodiments, bandwidth monitor 720 monitors bandwidth between asender and an appliance 200 by measuring an amount of bandwidth usedbetween the sender and the appliance 200. In some embodiments, bandwidthmonitor 720 monitors bandwidth between a receiver and an appliance 200by measuring an amount of bandwidth between the sender and theappliance. In a number of embodiments, bandwidth monitor 720 receivesany number of signals or an inputs from any one of or any combinationof: bandwidth measurer 450, bandwidth allocator 710, compression engine238, flow controller 220, a sender, an appliance 200 or a receiver, andusing the signals or inputs the bandwidth monitor 720 monitors thebandwidth. In some embodiments, the bandwidth monitor 720 monitors thebandwidth between a sender and a client, sender and a receiver orreceiver and a client using a bandwidth measurement or a plurality ofbandwidth measurements from any one of a bandwidth measurer 450,bandwidth allocator 710 or appliance 200.

In some embodiments, the bandwidth monitor 720 monitors any type ofbandwidth activity via one or more bandwidth measurers 450. Thebandwidth monitor 720 may interface to or communicate with a bandwidthmeasurer to obtain measures of bandwidth on a predetermined frequency,over predetermined time periods, ad-hoc or upon request. The bandwidthmonitor may use any type and form of API to receive events, updates orinformation regarding a measurement of bandwidth performed by abandwidth measurer. The bandwidth monitor 720 may monitor an amount ofbandwidth used in relation to a bandwidth allocation to an entity suchas a client. The bandwidth monitor 720 may monitor an amount ofbandwidth used in relation to a bandwidth credit, subscription orannuity of an entity such as a client.

Referring now to FIG. 8, an embodiment of steps of a method 800 forallocating a bandwidth credit is illustrated. In some aspects, themethod 800 comprises steps for allocating a bandwidth credit to anentity, such as a sender or a receiver. In many embodiments, anintermediary deployed between a sender and one or more receiversallocates a bandwidth credit of the sender or the receiver by comparingthe allocated bandwidth credit to a measurement of data transmissionrate. In some aspects, some steps of method 800 recite renewing anannuity of bandwidth credit of a sender or a receiver. In manyembodiments, an intermediary deployed between a sender and one or morereceivers renews an annuity of bandwidth credit of the sender bydetermining the allocated bandwidth credit to a measurement of datatransmission rate. In addition, the method 800 may comprise anyadditional steps which may be implemented in any order.

FIG. 8 illustrates an embodiment of a method 800 comprising steps 805through 840. At step 805, a bandwidth credit is allocated to a sender.In some embodiments, at Step 810 an annuity of bandwidth credit isallocated to the sender. At step 815, bandwidth usage is monitored bydetermining a ratio of compression and a rate of transmission. At step820, monitoring bandwidth usage of the sender over the predeterminedannuity period. At step 825, a difference between the rate oftransmission of the sender and the bandwidth usage of the sender isdetermined to fall below a predetermined threshold of the bandwidthcredit. In some embodiments, at step 830, a difference between thebandwidth usage of the sender over the annuity period and the annuity ofbandwidth credit is determined to exceed a predetermined threshold. Atstep 835 in response to the determination at step 825, an allocation ofa one-time bandwidth credit is communicated to the sender, such as basedon the difference. At step 840, in response to the determination at step830, a renewed allocation of the annuity bandwidth credit iscommunicated to the sender based on a second predetermined ratio ofcompression.

In further detail of step 805, any type and form of bandwidth credit maybe allocated to an entity, such as a sender. In some embodiments, anintermediary 200, allocates a bandwidth credit to a sender, a receiver,or even an intermediary 200. Sometimes, a bandwidth allocator 710 mayallocate a bandwidth credit to a sender or a receiver. In manyembodiments, a bandwidth credit allocated identifies an amount of datathe sender may transmit over a predetermined period of time. In someembodiments, a bandwidth credit allocated identifies an amount of datathe sender may transmit to one or more receivers. In a number ofembodiments, the bandwidth credit allocated identifies an amount of datathe sender may transmit to a receiver via an intermediary. In a varietyof embodiments, the bandwidth credit allocated identifies an amount ofdata of the sender compressed by the intermediary and transmitted to thereceiver. In some embodiments, a bandwidth credit is allocated bycomparing a bandwidth credit determined to a measurement of datatransmission rate between a sender and an intermediary 200. Sometimes, abandwidth credit is allocated by comparing a bandwidth credit determinedto a measurement of data transmission rate between a receiver and anintermediary 200. In many embodiments, a bandwidth credit to the senderor the receiver is allocated by comparing a bandwidth credit determinedto a measurement of data transmission rate traversing an intermediary.In many embodiments, allocating a bandwidth credit to the sender or thereceiver is completed using a determination of the compression of dataof the sender compressed by the intermediary 200 or using a compressionratio of the data of the sender compressed by the intermediary 200. In anumber of embodiments, a bandwidth credit is allocated using adetermination of the compression of data of the receiver compressed bythe intermediary 200, or using a compression ratio of the data of thesender compressed by the intermediary 200.

In some embodiments, a plurality of bandwidth credits may be allocatedto a plurality of senders. Each of the plurality of bandwidth creditsmay correspond to each one of the senders and identifying an amount ofdata each of the plurality of senders may transmit to one or morereceivers. In some embodiments, allocating a bandwidth credit to asender comprises identification of an amount of data the sender maytransmit in a one-time transmission to a receiver. In a number ofembodiments, allocating a bandwidth credit to a sender comprises anidentification of an amount of data the sender may transmit to areceiver over a plurality of transmissions within a predetermined periodof time. In a plurality of embodiments, allocating a bandwidth credit toa sender comprises an identification of an amount of data the sender maytransmit to a receiver over a plurality of transmissions not bounded byany period of time. Sometimes, allocating a bandwidth credit to a sendercomprises an identification of an amount of data the sender may transmitto a receiver via an intermediary 200. In some embodiments, allocating abandwidth credit to a sender comprises an identification of specificdata the sender may transmit to a receiver. In a number of embodiments,an identification of an amount of data the sender may transmit to areceiver is responsive to an information relating the compression ratiosof the data of the sender transmitted to the receiver and compressed bythe intermediary.

At step 810, any type and form of annuity of bandwidth credit may beallocated to an entity, such as a sender. In some embodiments, anintermediary 200 allocates an annuity of bandwidth credit to a sender ora receiver. In a number of embodiments, a bandwidth allocator 710allocates an annuity of bandwidth credit to a sender or a receiver. Inmany embodiments, an annuity of bandwidth credit allocated identifies anamount of data the sender may transmit over a predetermined period oftime, such as every day, week, month, year or any other annuity period.In some embodiments, an annuity of bandwidth credit allocated identifiesan amount of data the sender may transmit to one or more receivers. In anumber of embodiments, the annuity of bandwidth credit allocatedidentifies an amount of data the sender may transmit to a receiver viaan intermediary over the annuity period. In a variety of embodiments,the annuity of bandwidth credit allocated identifies an amount of dataof the sender compressed by the intermediary and transmitted to thereceiver over the annuity period. In some embodiments, an annuity ofbandwidth credit of the sender or the receiver is allocated using anamount of bandwidth determined by an appliance 200 or bandwidthallocator 710. In a number of embodiments, an annuity of bandwidthcredit is allocated by utilizing a determination of a data transmissionrate of the data sent by the sender. In a number of embodiments, anannuity of bandwidth credit is allocated by utilizing a determination ofa data transmission rate of the data sent by the receiver. In someembodiments, an annuity of bandwidth credit is allocated by using adetermination of compression or compression ratio of data transmitted bythe sender. Sometimes, an annuity of bandwidth credit is allocated byusing a determination of compression or compression ratio of datatransmitted by the receiver.

In some embodiments, a plurality of annuities of bandwidth credits areallocated to or for a plurality of senders. Each of the plurality ofannuities of bandwidth credits may correspond to each one of thesenders, identifying an amount of data each of the plurality of sendersmay transmit to one or more receivers. In some embodiments, allocatingan annuity of bandwidth credit to a sender, or a receiver, comprisesidentification of an amount of data the sender or the receiver maytransmit in a one-time transmission. In a number of embodiments,allocating an annuity of bandwidth credit comprises an identification ofan amount of data the sender may transmit to a receiver over a pluralityof transmissions within a predetermined period of time. In a pluralityof embodiments, allocating an annuity of bandwidth credit to a sendercomprises an identification of an amount of data the sender may transmitto a receiver over a plurality of transmissions not bounded by anyperiod of time. Sometimes, allocating an annuity of bandwidth credit toa sender comprises an identification of an amount of data the sender maytransmit to a receiver via an intermediary 200. In some embodiments,allocating an annuity of bandwidth credit to a sender comprises anidentification of specific data the sender may transmit to a receiver.In a number of embodiments, an identification of an amount of data thesender may transmit to a receiver is responsive to an informationrelating the compression ratios of the data of the sender transmitted tothe receiver and compressed by the intermediary. In some embodiments, anidentification of an amount of data the sender may transmit to areceiver is responsive to a determination of data transmission rate ofeither a sender or a receiver.

At step 815, bandwidth usage is monitored, for example, by determining aratio of compression and a rate of transmission. In some embodiments, abandwidth monitor 720 monitors the bandwidth usage. In a number of theembodiments, the bandwidth usage monitored is the bandwidth usage of thesender. Sometimes, the bandwidth usage monitored may be the bandwidthusage of the receiver. In some embodiments, the bandwidth usagemonitored is the bandwidth usage of the sender or the receivertraversing an intermediary 200. In a plurality of embodiments, bandwidthusage is monitored by determining a ratio of compression of data of thesender compressed by the intermediary. In many embodiments, bandwidthusage is monitored by determining a rate of transmission of data by thesender compressed by the intermediary. In some embodiments, bandwidthusage is monitored by determining a ratio of compression of data of thereceiver compressed by the intermediary. In many embodiments, bandwidthusage is monitored by determining a rate of transmission of data by thereceiver compressed by the intermediary. In some embodiments, bandwidthusage is monitored by determining a ratio of compression of data of thereceiver or the sender traversing an intermediary within a predeterminedamount of time. In many embodiments, the ratio of compression of data ofthe receiver or the sender is determined by determining an average of acompression of data compressed by the intermediary over a predeterminedperiod of time. In many embodiments, the ratio of compression of data ofthe receiver or the sender is determined by determining a median of acompression of data compressed by the intermediary over a predeterminedperiod of time. In many embodiments, the rate of transmission ofcompressed data is determined by establishing or estimating an averagerate of transmission of compressed data over a predetermined period oftime. In many embodiments, the rate of transmission of compressed datais determined by establishing or estimating a median rate oftransmission of compressed data over a predetermined period of time. Insome embodiments, bandwidth usage is monitored by determining a ratio ofcompression data of the sender compressed by the intermediary and a rateof transmission of compressed data of the sender transmitted by theintermediary to one or more receivers. In a variety of embodiments,bandwidth usage is monitored by measuring or monitoring bandwidth usageby any one of, or any combination of: a sender transmitting the data,the sender receiving the data, an appliance 200 receiving the data, theappliance 200 transmitting the data, a receiver receiving the data andthe receiver transmitting the data.

At step 820, bandwidth usage of an entity, such as a sender, ismonitored over the annuity period. In one embodiment, the annuity periodcomprises a predetermined annuity period. In many embodiments, theannuity period is a predetermined duration of time. In some embodiments,the bandwidth usage of the sender is monitored over a relatively longerannuity period, such as a week, a month or a year. In some embodiments,the bandwidth usage of the sender is monitored over a relatively shorterannuity period, such as a second, a minute, an hour, or a range ofhours. In some embodiments, the annuity period is a period of timedefined by a sender, receiver or an intermediary. In a plurality ofembodiments, the annuity period is defined by a user transmittinginformation or data from the sender. In a number of embodiments, theannuity period is defined by a user receiving information or data on thereceiver. In a plurality of embodiments, an operator of the intermediary200 sets the predetermined annuity period. In some embodiments, theintermediary 200 determines the predetermined annuity period based onthe statistics of the bandwidth usage by the sender or the receiver. Insome embodiments, bandwidth measurer 450 or the bandwidth monitor 720determines the predetermined annuity period. In a variety ofembodiments, bandwidth usage is monitored by measuring bandwidth usageby any one of, or any combination of: a sender transmitting the data,the sender receiving the data, an appliance 200 receiving the data, theappliance 200 transmitting the data, a receiver receiving the data andthe receiver transmitting the data.

At step 825, a difference between the rate of transmission of the senderand the bandwidth usage of the sender may be determined to fall below apredetermined threshold of the bandwidth credit. In some embodiments,the flow controller 220 determines that a difference between the rate ofa transmission of the sender and the bandwidth usage of the sender fallsbelow a predetermined threshold of the bandwidth credit. In variousembodiments, the compression engine 238, the bandwidth measurer 450, thebandwidth allocator 710, the bandwidth monitor 720, or any othercomponent of the intermediary 200 determines the difference between therate of transmission of the sender and the bandwidth usage of thesender. In many embodiments, the predetermined threshold is a range,such as a predetermined threshold range. The difference between the rateof transmission and the bandwidth usage of the sender may fall within apredetermined threshold range. In a plurality of embodiments, thedifference between the rate of transmission and the bandwidth usage ofthe sender falls outside of a predetermined threshold range.Predetermined threshold may be any value of the bandwidth, any amount ofdata or any amount of data per period of time. Predetermined thresholdmay be any number or a value. Predetermined threshold range may be anyrange of bandwidth, any range of data amount or any range of data amountper period of time. In some embodiments, the intermediary 200, or anyintermediary 200 component determines that a difference between the rateof transmission of the sender and the bandwidth usage of the senderfalls above a predetermined threshold of the bandwidth credit. In anumber of embodiments, the predetermined threshold of the bandwidthcredit is determined by comparing the amount of data of the compresseddata packets 495 to the amount of data of the data packets 480corresponding to the compressed data packets 495, before the same datapackets 480 were compressed by the intermediary 200. In a number ofembodiments, the predetermined threshold of the bandwidth credit isdetermined by using the amount of data of the compressed data packets495 and the amount of data of the data packets 480 corresponding to thecompressed data packets 495, before the same data packets 480 werecompressed by the intermediary 200. In some embodiments, thepredetermined threshold is determined by determining the compressionratios of the compressed data packets 495 in relation to the datapackets 480 corresponding to the compressed data packets 495 beforebeing compressed by the intermediary 200.

At step 830, a difference between the bandwidth usage of the sender overthe annuity period and the annuity of bandwidth credit may be determinedto exceed a predetermined threshold. In some embodiments, thepredetermined threshold is a predetermined threshold of a bandwidthcredit. In some embodiments, the flow controller 220 determines that adifference between the bandwidth usage of the sender over the annuityperiod and the annuity of bandwidth credit exceeds a predeterminedthreshold. In various embodiments, the compression engine 238, thebandwidth measurer 450, the bandwidth allocator 710, the bandwidthmonitor 720, or any other component of the intermediary 200 determinesthe difference between the bandwidth usage of the sender over theannuity period and the annuity of bandwidth credit. In many embodiments,the predetermined threshold is a predetermined threshold range. Thedifference between the bandwidth usage of the sender over the annuityperiod and the annuity of bandwidth credit may fall within apredetermined threshold range. In a plurality of embodiments, thedifference between the rate of transmission and the bandwidth usage ofthe sender falls outside of a predetermined threshold range.Predetermined threshold may be any value of the bandwidth, any amount ofdata or any amount of data per period of time. Predetermined thresholdmay be any number or a value. Predetermined threshold range may be anyrange of bandwidth, any range of data amount or any range of data amountper period of time. In some embodiments, the intermediary 200, or anyintermediary 200 component determines that a difference between the rateof transmission of the sender and the bandwidth usage of the senderfalls above a predetermined threshold. In a number of embodiments, thepredetermined threshold is determined by comparing the amount of data ofthe compressed data packets 495 to the amount of data of the datapackets 480 corresponding to the compressed data packets 495, before thesame data packets 480 were compressed by the intermediary 200. In anumber of embodiments, the predetermined threshold of the bandwidthcredit is determined by using the amount of data of the compressed datapackets 495 and the amount of data of the data packets 480 correspondingto the compressed data packets 495, before the same data packets 480were compressed by the intermediary 200. In some embodiments, thepredetermined threshold is determined by determining the compressionratios of the compressed data packets 495 in relation to the datapackets 480 corresponding to the compressed data packets 495 beforebeing compressed by the intermediary 200.

At step 835, in response to the determination, an allocation of aone-time bandwidth credit may be communicated to the sender based on thedifference. In some embodiments, an allocation of a one-time bandwidthcredit to a receiver is communicated. In some embodiments, communicatingan allocation of a one-time bandwidth credit is based on the differencebetween the bandwidth usage of the sender over the annuity period andthe annuity of bandwidth credit. In many embodiments, communicating anallocation of a one-time bandwidth credit is based on the differencebetween the bandwidth usage of the sender or the receiver over theannuity period and the annuity of bandwidth credit exceeding or notexceeding the predetermined threshold. In some embodiments,communicating an allocation of a one-time bandwidth credit is based onthe difference between the rate of transmission of the sender or thereceiver and the bandwidth usage. In a plurality of embodiments,communicating an allocation of a one-time bandwidth credit is based onthe difference between the rate of transmission of the sender or thereceiver and the bandwidth usage of the sender or the receiver fallingbelow or above a predetermined threshold of the bandwidth credit. Insome embodiments, communicating an allocation of a one-time bandwidthcredit is in response to the determination. In a variety of embodiments,communicating an allocation of a one-time bandwidth credit is inresponse to the monitoring of the bandwidth usage. In a number ofembodiments, communicating an allocation of a one-time bandwidth creditis in response to the monitoring of the bandwidth usage and thedetermining a difference between the rate of transmission of the senderor the receiver and the bandwidth usage of the sender or the receiver.In many embodiments, communicating an allocation of a one-time bandwidthcredit is in response to the monitoring of the bandwidth usage and thedetermining of the difference between the bandwidth usage of the senderor the receiver over the annuity period and the annuity of bandwidthcredit.

At step 840, in response to the determination, a renewed allocation ofthe annuity bandwidth credit is communicated to a sender based on asecond predetermined ratio of compression. In a number of embodiments, arenewed allocation of the annuity bandwidth credit to a receiver iscommunicated. In some embodiments, communicating a renewed allocation ofthe annuity bandwidth credit is based on the difference between thebandwidth usage of the sender or the receiver over the annuity periodand the annuity of bandwidth credit. In many embodiments, communicatinga renewed allocation of the annuity bandwidth credit is based on thedifference between the bandwidth usage of the sender or the receiverover the annuity period and the annuity of bandwidth credit, exceedingor not exceeding the predetermined threshold. In some embodiments,communicating a renewed allocation of the annuity bandwidth credit isbased on the difference between the rate of transmission of the senderor the receiver and the bandwidth usage of the sender or the receiver.In a plurality of embodiments, communicating an allocation of a one-timebandwidth credit is based on the difference between the rate oftransmission of the sender or the receiver and the bandwidth usage ofthe sender or the receiver falling below or above a predeterminedthreshold of the bandwidth credit. In some embodiments, communicating anallocation of a one-time bandwidth credit is in response to thedetermination. In a variety of embodiments, communicating an allocationof a one-time bandwidth credit is in response to the monitoring of thebandwidth usage of the sender or the receiver. In a number ofembodiments, communicating an allocation of a one-time bandwidth creditis in response to the monitoring of the bandwidth usage and thedetermining a difference between the rate of transmission of the senderor the receiver and the bandwidth usage of the sender or the receiver.In many embodiments, communicating an allocation of a one-time bandwidthcredit is in response to the monitoring of the bandwidth usage and thedetermining of the difference between the bandwidth usage of the senderor the receiver over the annuity period and the annuity of bandwidthcredit.

Many alterations and modifications may be made by those having ordinaryskill in the art without departing from the spirit and scope of thedisclosure. Therefore, it should be clear that any of the embodimentspresented above may be combined with any other embodiments above forexpressing any other aspects of the disclosure. It should also beexpressly understood that the illustrated embodiments have been shownonly for the purposes of example and should not be taken as limiting thedisclosure, which is defined by the following claims. These claims areto be read as including what they set forth literally and also thoseequivalent elements which are insubstantially different, even though notidentical in other respects to what is shown and described in the aboveillustrations.

1. A method for allocating, by an intermediary between a sender and oneor more receivers, a bandwidth credit of the sender by comparing theallocated bandwidth credit to a measurement of data transmission ratesvia the intermediary and compression of data by the intermediary, themethod comprising: a) allocating, to a sender, a bandwidth creditidentifying an amount of data the sender may transmit over apredetermined time period to the one or more receivers via anintermediary, the intermediary compressing data of the sendertransmitted to the one or more receivers; b) monitoring, by theintermediary, bandwidth usage by determining a ratio of compression ofdata of the sender compressed by the intermediary and a rate oftransmission of compressed data of the sender transmitted by theintermediary to the one or more receivers; c) determining, by theintermediary, that a difference between the rate of transmission of thesender and the bandwidth usage of the sender falls below a predeterminedthreshold of the bandwidth credit; and d) communicating, by theintermediary responsive to the determination, an allocation of aone-time bandwidth credit to the sender based on the difference.
 2. Themethod of claim 1, wherein step (a) further comprises allocating, to aplurality of senders, a plurality of bandwidth credits, each of theplurality of bandwidth credits identifying an amount of data each of theplurality of senders may transmit over a predetermined time period to atleast one receiver.
 3. The method of claim 1, wherein step (c) furthercomprises determining, by the intermediary, that the difference betweenthe rate of transmission of the sender and the bandwidth usage of thesender falls within a predetermined threshold range of the bandwidthcredit.
 4. The method of claim 1, further comprising identifying, by theone-time bandwidth credit, a second predetermined amount of data thesender may send to the one or more receivers within the predeterminedtime period.
 5. The method of claim 1, further comprising identifying,by the one-time bandwidth credit, a second predetermined amount of datathe sender may send to the one or more receivers within a secondpredetermined amount of time.
 6. The method of claim 1, furthercomprising identifying, by the one-time bandwidth credit, apredetermined amount of additional data the sender may send to anidentified receiver via the intermediary.
 7. The method of claim 1,wherein step (b) further comprises monitoring, by the intermediary, thebandwidth usage by determining a rate of transmission of datatransmitted from the one or more receivers via the intermediary to thesender.
 8. The method of claim 1, further comprising determining, by theintermediary in response to monitoring, that a difference between therate of transmission of the sender and the bandwidth usage of the senderfalls below a predetermined threshold of the bandwidth credit.
 9. Themethod of claim 1, further comprising: e) allocating, to a receiver, asecond bandwidth credit identifying an amount of data the receiver maytransmit over a predetermined time period to the sender via theintermediary; f) monitoring, by the intermediary, bandwidth usage of thereceiver by determining a ratio of compression of data of the receivercompressed by the intermediary and a rate of transmission of compresseddata of the receiver transmitted by the intermediary to the sender; g)determining, by the intermediary, that a second difference between therate of transmission of the receiver and the bandwidth usage of thereceiver falls below a second predetermined threshold of the secondbandwidth credit; and h) communicating, by the intermediary responsiveto the determination, an allocation of a second one-time bandwidthcredit to the receiver.
 10. A method for renewing, by an intermediarybetween a sender and one or more receivers, an annuity of bandwidthcredit of the sender by comparing the allocated bandwidth credit to ameasurement of data transmission rate via the intermediary andcompression of data by the intermediary, the method comprising steps of:a) allocating, to a sender, an annuity of bandwidth credit identifyingan amount of data the sender may transmit within a predetermined annuityperiod to one or more receiver via an intermediary, the intermediarycompressing data of the sender transmitted to the one or more receivers;b) monitoring, by the intermediary, bandwidth usage of the senderbetween the intermediary and the one or more receivers over thepredetermined annuity period based on determining a ratio of compressionof data of the sender compressed by the intermediary and a rate oftransmission of compressed data of the sender transmitted by theintermediary; c) determining, by the intermediary, that a differencebetween the bandwidth usage of the sender over the annuity period andthe annuity of bandwidth credit exceeds a predetermined threshold; andd) communicating, by the intermediary responsive to the determination, arenewed allocation of the annuity bandwidth credit to the sender basedon a second predetermined ratio of compression.
 11. The method of claim10, further comprising identifying, by the annuity of bandwidth credit,a plurality of amounts of data the sender may transmit over a pluralityof predetermined annuity periods.
 12. The method of claim 10, whereinstep (b) further comprising monitoring, by the intermediary, bandwidthusage of the sender between the intermediary and the one or morereceivers over the predetermined annuity period based on determining aratio of compression of data of the sender compressed by theintermediary and a rate of transmission of compressed data of the sendertransmitted by the intermediary.
 13. The method of claim 10, furthercomprising identifying, by the renewed allocation, a second amount ofdata the sender may transmit over a second predetermined annuity periodvia the intermediary.
 14. The method of claim 10, further comprisingidentifying, by the renewed allocation, a second amount of data thesender may transmit over the predetermined annuity period via theintermediary.
 15. The method of claim 10, further comprising: e)allocating, to a receiver, a second annuity of bandwidth creditidentifying an amount of data the receiver may transmit over a secondpredetermined annuity period to the sender via the intermediary; f)monitoring, by the intermediary, a second bandwidth usage of thereceiver between the intermediary and the sender over the secondpredetermined annuity period based on determining a ratio of compressionof data of the receiver compressed by the intermediary and a rate oftransmission of compressed data of the receiver transmitted by theintermediary; g) determining, by the intermediary, that a differencebetween the second bandwidth usage and the second annuity of bandwidthcredit exceeds a predetermined threshold; and h) communicating, by theintermediary responsive to the determination, a second renewedallocation of the annuity bandwidth credit to the receiver.
 16. Anintermediary between a sender and one or more receivers for providing achange in bandwidth allocation of a sender using a measurement of datatransmission rate via the intermediary and compression of data by theintermediary, the intermediary comprising: a bandwidth allocatorallocating to a sender a bandwidth credit identifying an amount of datathe may transmit over a predetermined time period via the intermediary,the intermediary compressing data of the sender transmitted to one ormore receivers; a bandwidth monitor monitoring bandwidth usage bydetermining a ratio of compression of data of the sender compressed bythe intermediary and a rate of transmission of compressed data of thesender transmitted by the intermediary; a flow controller determiningthat a difference between the rate of transmission of the sender and thebandwidth usage of the sender falls below a predetermined threshold ofthe bandwidth credit; and wherein the intermediary communicates, inresponse to the determination, a change in the bandwidth credit to thesender based on the difference.
 17. The intermediary of claim 16,wherein the flow controller determines that a difference between thebandwidth usage of the sender over the predetermined time period and thebandwidth credit exceeds a predetermined threshold; and the intermediarycommunicating, responsive to the determination, a renewal of thebandwidth credit to the sender, the renewal of the bandwidth creditidentifying an amount of data the sender may transmit within a secondpredetermined time period via the intermediary.
 18. The intermediary ofclaim 16, wherein the flow controller determines that the differencebetween the rate of transmission of the sender and the bandwidth usageof the sender falls within a predetermined threshold range of thebandwidth credit.
 19. The intermediary of claim 16, wherein thebandwidth allocator determines a one-time bandwidth credit andresponsive to the determination the intermediary communicates theone-time bandwidth credit to the sender.
 20. The intermediary of claim17, wherein the flow controller monitors the bandwidth usage of thesender between the intermediary and the one or more receivers over thepredetermined annuity period based on determining a ratio of compressionof data of the sender compressed by the intermediary and a rate oftransmission of compressed data of the sender received by the one ormore receivers.